<PAGE>   1
                                                                  EXHIBIT 10.1.6




                          CHESAPEAKE ENERGY CORPORATION

                         2000 EMPLOYEE STOCK OPTION PLAN


<PAGE>   2


                          CHESAPEAKE ENERGY CORPORATION
                         2000 EMPLOYEE STOCK OPTION PLAN

                                Table of Contents


<TABLE>
<S>                                                                                                              <C>
ARTICLE I - PURPOSE...............................................................................................1
         Section 1.1       Purpose................................................................................1
         Section 1.2       Establishment..........................................................................1
         Section 1.3       Shares Subject to the Plan.............................................................1


ARTICLE II - DEFINITIONS..........................................................................................1


ARTICLE III - ADMINISTRATION......................................................................................2
         Section 3.1       Administration of the Plan; the Committee..............................................2
         Section 3.2       Committee to Make Rules and Interpret Plan.............................................3


ARTICLE IV - GRANT OF OPTIONS.....................................................................................3


ARTICLE V - ELIGIBILITY...........................................................................................3


ARTICLE VI - STOCK OPTIONS........................................................................................4
         Section 6.1       Grant of Options.......................................................................4
         Section 6.2       Conditions of Options..................................................................4


ARTICLE VII - STOCK ADJUSTMENTS...................................................................................5


ARTICLE VIII - GENERAL............................................................................................5
         Section 8.1       Amendment or Termination of Plan.......................................................5
         Section 8.2       Acceleration of Otherwise Unexercisable Stock Options on Death, Disability or
                           Other Special Circumstances............................................................6
         Section 8.3       Nonassignability.......................................................................6
         Section 8.4       Withholding Taxes......................................................................6
         Section 8.5       Amendments to Options..................................................................6
         Section 8.6       Regulatory Approval and Listings.......................................................6
         Section 8.7       Right to Continued Employment..........................................................6
         Section 8.8       Reliance on Reports....................................................................6
         Section 8.9       Construction...........................................................................7
         Section 8.10      Governing Law..........................................................................7


ARTICLE IX - ACCELERATION OF OPTIONS UPON CORPORATE EVENT.........................................................7
         Section 9.1       Procedures for Acceleration and Exercise...............................................7
         Section 9.2       Certain Additional Payments by the Company.............................................7
</TABLE>


<PAGE>   3


                                    ARTICLE I

                                     PURPOSE

     SECTION 1.1 Purpose. This Stock Option Plan is established by Chesapeake
Energy Corporation (the "Company") to create incentives which are designed to
motivate Eligible Employees to put forth maximum effort toward the success and
growth of the Company and to enable the Company to attract and retain
experienced individuals who by their position, ability and diligence are able to
make important contributions to the Company's success. Toward these objectives,
the Plan provides for the granting of Options to Eligible Employees on the terms
and subject to the conditions set forth in the Plan.

     SECTION 1.2 Establishment. The Plan is effective as of April 26, 2000 and
for a period of 10 years from such date. The Plan will terminate on April 25,
2010; however, it will continue in effect until all matters relating to the
exercise of Options and administration of the Plan have been settled.

     SECTION 1.3 Shares Subject to the Plan. Subject to Articles IV, VII and IX
of this Plan, shares of stock covered by Options shall consist of Two Million
Five Hundred Thousand (2,500,000) shares of Common Stock.

                                   ARTICLE II

                                   DEFINITIONS

     SECTION 2.1 "Board" means the Board of Directors of the Company.

     SECTION 2.2 "Code" means the Internal Revenue Code of 1986, as amended.
Reference in the Plan to any Section of the Code shall be deemed to include any
amendments or successor provisions to such Section and any regulations under
such Section.

     SECTION 2.3 "Committee" has the meaning set forth in Section 3.1.

     SECTION 2.4 "Common Stock" means the common stock, par value $.01 per
share, of the Company and, after substitution, such other stock as shall be
substituted therefor as provided in Article VII or Article IX of the Plan.

     SECTION 2.5 "Date of Grant" means the date on which the granting of an
Option is authorized by the Committee or such later date as may be specified by
the Committee in such authorization.

     SECTION 2.6 "Disability" has the meaning set forth in Section 22(e)(3) of
the Code.

     SECTION 2.7 "Eligible Employee" means any employee of the Company, a
Subsidiary or a partnership or limited liability company which the Company
controls.

     SECTION 2.8 "Exchange Act" means the Securities Exchange Act of 1934, as
amended.

     SECTION 2.9 "Executive Officer Participants" means Participants who are
subject to the provisions of Section 16 of the Exchange Act with respect to the
Common Stock.

     SECTION 2.10 "Fair Market Value" means, as of any date, (i) if the
principal market for the Common Stock is a national securities exchange or the
Nasdaq stock market, the closing price of the Common Stock on that date on the
principal exchange on which the Common Stock is then listed or admitted to
trading; or (ii) if sale prices are not available or if the principal market for
the Common Stock is not a national securities exchange and the Common Stock is
not quoted on the Nasdaq stock market, the average of the highest bid and lowest
asked prices for the Common Stock on such day as reported on the Nasdaq OTC
Bulletin Board Service or by the National Quotation Bureau, Incorporated or a
comparable service. If the day is not a business day, and as a result, clauses
(i) and (ii) are inapplicable, the Fair Market Value of the Common Stock shall
be determined as of the last preceding business day. If clauses (i) and (ii) are
otherwise inapplicable, the Fair Market Value of the Common Stock shall be
determined in good faith by the Committee.


<PAGE>   4


     SECTION 2.11 "Non-Executive Officer Participants" means Participants who
are not subject to the provisions of Section 16 of the Exchange Act.

     SECTION 2.12 "Nonqualified Stock Option" means an option to purchase shares
of Common Stock which is not an incentive stock option within the meaning of
Section 422(b) of the Code.

     SECTION 2.13 "Option" means a Nonqualified Stock Option granted under
Article VI of the Plan.

     SECTION 2.14 "Option Agreement" means any written instrument that
establishes the terms, conditions, restrictions, and/or limitations applicable
to an Option in addition to those established by this Plan and by the
Committee's exercise of its administrative powers.

     SECTION 2.15 "Participant" means an Eligible Employee to whom an Option has
been granted by the Committee under the Plan.

     SECTION 2.16 "Plan" means the Chesapeake Energy Corporation 2000 Employee
Stock Option Plan.

     SECTION 2.17 "Regular Stock Option Committee" means a committee designated
by the Board which shall consist of not less than two members of the Board.

     SECTION 2.18 "Special Stock Option Committee" means a committee designated
by the Board which shall consist of not less than two members of the Board who
meet the definition of "non-employee directors" pursuant to Rule 16b-3, or any
successor rule, promulgated under Section 16 of the Exchange Act.

     SECTION 2.19 "Subsidiary" shall have the same meaning set forth in Section
424 of the Code.

                                   ARTICLE III

                                 ADMINISTRATION

     SECTION 3.1 Administration of the Plan; the Committee. The Regular Stock
Option Committee shall administer the Plan with respect to Non-Executive Officer
Participants, including the grant of Options, and the Special Stock Option
Committee shall administer the Plan with respect to Executive Officer
Participants, including the grant of Options. Accordingly, as used in the Plan,
the term "Committee" shall mean the Regular Stock Option Committee if it refers
to Plan administration affecting Non-Executive Officer Participants or the
Special Stock Option Committee if it refers to Plan administration affecting
Executive Officer Participants. If in either case the Committee does not exist,
or for any other reason determined by the Board, the Board may take any action
under the Plan that would otherwise be the responsibility of the Committee.

     Unless otherwise provided in the by-laws of the Company or resolutions
adopted from time to time by the Board establishing the Committee, the Board may
from time to time remove members from, or add members to, the Committee.
Vacancies on the Committee, however caused, shall be filled by the Board. The
Committee shall hold meetings at such times and places as it may determine. A
majority of the Committee shall constitute a quorum, and the acts of a majority
of the members present at any meeting at which a quorum is present shall be the
valid acts of the Committee. Any action which may be taken at a meeting of the
Committee may be taken without a meeting if all the members of the Committee
consent to the action in writing.

     Subject to the provisions of the Plan, the Committee shall have exclusive
power to:

          (a) Select the Eligible Employees to participate in the Plan.

          (b) Determine the time or times when Options will be granted.


                                      -2-
<PAGE>   5


          (c) Determine the number of shares of Common Stock subject to any
     Option, all the terms, conditions (including performance requirements),
     restrictions and/or limitations, if any, of an Option, including the time
     and conditions of exercise or vesting, and the terms of any Option
     Agreement, which may include the waiver or amendment of prior terms and
     conditions or acceleration of the vesting or exercise of an Option under
     certain circumstances determined by the Committee.

          (d) Determine whether Options will be granted singly or in
     combination.

          (e) Take any and all other action it deems necessary or advisable for
     the proper operation or administration of the Plan.

     SECTION 3.2 Committee to Make Rules and Interpret Plan. The Committee in
its sole discretion shall have the authority, subject to the provisions of the
Plan, to establish, adopt, or revise such rules and regulations and to make all
such determinations relating to the Plan as it may deem necessary or advisable
for the administration of the Plan. The Committee reserves the right to modify
outstanding Options and awards unilaterally in any manner that is not adverse to
the Option or award holder. The Committee's interpretation of the Plan or any
Options granted pursuant hereto and all decisions and determinations by the
Committee with respect to the Plan shall be final, binding, and conclusive on
all parties.

                                   ARTICLE IV

                                GRANT OF OPTIONS

     The Committee may, from time to time, grant Options to one or more
Participants, provided, however, that:

          (a) At least a majority of the shares of Common Stock underlying
     Options granted under the Plan, during the shorter of the three-year period
     commencing on the effective date of the Plan or the term of the Plan, must
     be granted to employees who are not Executive Officer Participants or
     directors of the Company.

          (b) Any shares of Common Stock related to Options which terminate by
     expiration, forfeiture, cancellation or otherwise without the issuance of
     shares of Common Stock shall be available again for grant under the Plan.

          (c) Common Stock delivered by the Company upon exercise of an Option
     under the Plan will be authorized and unissued shares or issued shares
     which have been reacquired by the Company (i.e., treasury shares).

          (d) The Committee shall, in its sole discretion, determine the manner
     in which fractional shares arising under this Plan shall be treated.

          (e) Upon the exercise of any Option, the Company shall issue and
     deliver to the Participant who exercised the Option a certificate
     representing the number of shares of Common Stock purchased thereby.

                                    ARTICLE V

                                   ELIGIBILITY

     Subject to the provisions of the Plan, the Committee shall, from time to
time, select from the Eligible Employees those to whom Options shall be granted
and shall establish in the related Option Agreements the terms, conditions,
restrictions and/or limitations, if any, applicable to the Options in addition
to those set forth in the Plan and the administrative rules and regulations
issued by the Committee.


                                      -3-
<PAGE>   6


                                   ARTICLE VI

                                  STOCK OPTIONS

     SECTION 6.1 Grant of Options. The Committee may, from time to time, subject
to the provisions of the Plan and such other terms and conditions as it may
determine, grant Nonqualified Stock Options to Eligible Employees. Each grant of
an Option shall be evidenced by an Option Agreement executed by the Company and
the Participant, and shall contain such terms and conditions and be in such form
as the Committee may from time to time approve, subject to the requirements of
Section 6.2.

     SECTION 6.2 Conditions of Options. Each Option so granted shall be subject
to the following conditions:

          (a) Exercise Price. The Option Agreement for each Option shall state
     the exercise price which shall be set by the Committee on the Date of
     Grant. No Option shall be granted at an exercise price which is less than
     the Fair Market Value of the Common Stock on the Date of Grant, except that
     Options for the purchase of up to ten percent (10%) of the shares subject
     to the Plan may be granted at an exercise price which is not less than
     eighty-five percent (85%) of the Fair Market Value of the Common Stock on
     the Date of Grant.

          (b) Form of Payment. The payment of the exercise price of an Option
     shall be subject to the following:

               (i)   The full exercise price for shares of Common Stock
                     purchased upon the exercise of any Option shall be paid at
                     the time of such exercise (except that, in the case of an
                     exercise arrangement approved by the Committee and
                     described in clause (iii) below, payment may be made as
                     soon as practicable after the exercise).

               (ii)  The exercise price shall be payable in cash (including a
                     check acceptable to the Committee, bank draft or money
                     order) or by tendering, by either actual delivery of shares
                     or by attestation, shares of Common Stock acceptable to the
                     Committee and valued at Fair Market Value as of the day of
                     exercise, or any combination thereof, as determined by the
                     Committee.

               (iii) The Committee may permit a Participant to elect to pay the
                     exercise price upon the exercise of an Option by
                     irrevocably authorizing a third party to sell shares of
                     Common Stock (or a sufficient portion of the shares)
                     acquired upon exercise of the Option and remit to the
                     Company a sufficient portion of the sale proceeds to pay
                     the entire exercise price and any tax withholding resulting
                     from such exercise.

          (c) Exercise of Options. Options granted under the Plan shall be
     exercisable, in whole or in such installments and at such times, and shall
     expire at such time, as shall be provided by the Committee in the Option
     Agreement. Exercise of an Option shall be by written notice stating the
     election to exercise in the form and manner determined by the Committee.
     Every share of Common Stock acquired through the exercise of an Option
     shall be deemed to be fully paid at the time of exercise and payment of the
     exercise price.

          (d) Other Terms and Conditions. Among other conditions that may be
     imposed by the Committee, if deemed appropriate, are those relating to (i)
     the period or periods and the conditions of exercisability of any Option;
     (ii) the minimum periods during which Participants must be employed by the
     Company or its Subsidiaries, or must hold Options before they may be
     exercised; (iii) the minimum periods during which shares acquired upon
     exercise must be held before sale or transfer shall be permitted; (iv)
     conditions under which such Options or shares may be subject to forfeiture;
     (v) the frequency of exercise


                                      -4-
<PAGE>   7


     or the minimum or maximum number of shares that may be acquired at any one
     time and (vi) the achievement by the Company of specified performance
     criteria.

          (e) Application of Funds. The proceeds received by the Company from
     the sale of Common Stock issued upon the exercise of Options will be used
     for general corporate purposes.

          (f) Shareholder Rights. No Participant shall have any rights as a
     shareholder with respect to any share of Common Stock subject to an Option
     prior to the purchase of such share of Common Stock by exercise of the
     Option.

                                   ARTICLE VII

                                STOCK ADJUSTMENTS

     Subject to the provisions of Article IX of this Plan, in the event that the
shares of Common Stock, as presently constituted shall be changed into or
exchanged for a different number or kind or shares of stock or other securities
of the Company or of another corporation (whether by reason of merger,
consolidation, recapitalization, reclassification, stock split, combination of
shares or otherwise), or if the number of such shares of Common Stock shall be
increased through the payment of a stock dividend, or a dividend on the shares
of Common Stock or rights or warrants to purchase securities of the Company
shall be made, then there shall be substituted for or added to each share
available under and subject to the Plan as provided in Section 1.3 hereof, and
each share then subject or thereafter subject or which may become subject to
Options under the Plan, the number and kind of shares of stock or other
securities into which each outstanding share of Common Stock shall be so changed
or for which each such share shall be exchanged or to which each such share
shall be entitled, as the case may be, on a fair and equivalent basis in
accordance with the applicable provisions of Section 424 of the Code; provided,
however, in no such event will such adjustment result in a modification of any
Option as defined in Section 424(h) of the Code. In the event there shall be any
other change in the number or kind of the outstanding shares of Common Stock, or
any stock or other securities into which the Common Stock shall have been
changed or for which it shall have been exchanged, then if the Committee shall,
in its sole discretion, determine that such change equitably requires an
adjustment in the shares available under and subject to the Plan, or in any
Option theretofore granted or which may be granted under the Plan, such
adjustments shall be made in accordance with such determination, except that no
adjustment of the number of shares of Common Stock available under the Plan or
to which any Option relates that would otherwise be required shall be made
unless and until such adjustment either by itself or with other adjustments not
previously made would require an increase or decrease of at least 1% of the
number of shares of Common Stock available under the Plan or to which any Option
relates immediately prior to the making of such adjustment (the "Minimum
Adjustment"). Any adjustment representing a change of less than such minimum
amount shall be carried forward and made as soon as such adjustment together
with other adjustments required by this Article VII and not previously made
would result in a Minimum Adjustment. Notwithstanding the foregoing, any
adjustment required by this Article VII which otherwise would not result in a
Minimum Adjustment shall be made with respect to shares of Common Stock relating
to any Option immediately prior to exercise of such Option.

     No fractional shares of Common Stock or units of other securities shall be
issued pursuant to any such adjustment, and any fractions resulting from any
such adjustment shall be eliminated in each case by rounding downward to the
nearest whole share.

                                  ARTICLE VIII

                                     GENERAL

     SECTION 8.1 Amendment or Termination of Plan. The Board may suspend or
terminate the Plan at any time. In addition, the Board may, from time to time,
amend the Plan in any manner in accordance with applicable federal or state laws
or regulations.


                                      -5-
<PAGE>   8


     SECTION 8.2 Acceleration of Otherwise Unexercisable Stock Options on Death,
Disability or Other Special Circumstances. The Committee, in its sole
discretion, may permit (i) a Participant who terminates employment due to a
Disability, (ii) the personal representative of a deceased Participant, or (iii)
any other Participant who terminates employment upon the occurrence of special
circumstances (as determined by the Committee) to purchase all or any part of
the shares subject to any unvested Option on the date of the Participant's
termination of employment due to a Disability, death or special circumstances,
or as the Committee otherwise so determines. With respect to Options which have
already vested at the date of such termination or the vesting of which is
accelerated by the Committee in accordance with the foregoing provision, the
Participant or the personal representative of a deceased Participant shall have
the right to exercise such vested Options within such period(s) as the Committee
shall determine.

     SECTION 8.3 Nonassignability. Options are not transferable otherwise than
by will or the laws of descent and distribution. Any attempted transfer,
assignment, pledge, hypothecation or other disposition of, or the levy of
execution, attachment or similar process upon, any Option contrary to the
provisions hereof shall be void and ineffective, shall give no right to any
purported transferee, and may, at the sole discretion of the Committee, result
in forfeiture of the Option involved in such attempt.

     SECTION 8.4 Withholding Taxes. A Participant must pay to the Company the
amount of taxes required by law upon the exercise of an Option in cash.

     SECTION 8.5 Amendments to Options. The Committee may at any time
unilaterally amend the terms of any Option Agreement, whether or not the Option
granted thereunder is presently exercisable or vested, to the extent it deems
appropriate; provided, however, that any such amendment which is adverse to the
Participant shall require the Participant's consent.

     SECTION 8.6 Regulatory Approval and Listings. The Company shall use its
best efforts to file with the Securities and Exchange Commission as soon as
practicable following the date this Plan is effective, and keep continuously
effective and usable, a Registration Statement on Form S-8 with respect to
shares of Common Stock subject to Options hereunder. Notwithstanding anything
contained in this Plan to the contrary, the Company shall have no obligation to
issue or deliver certificates representing shares of Common Stock evidencing
Options prior to:

          (a) the obtaining of any approval from, or satisfaction of any waiting
     period or other condition imposed by, any governmental agency which the
     Committee shall, in its sole discretion, determine to be necessary or
     advisable;

          (b) the listing of such shares on any exchange on which the Common
     Stock may be listed; and

          (c) the completion of any registration or other qualification of such
     shares under any state or federal law or regulation of any governmental
     body which the Committee shall, in its sole discretion, determine to be
     necessary or advisable.

     SECTION 8.7 Right to Continued Employment. Participation in the Plan shall
not give any Participant any right to remain in the employ of the Company or any
Subsidiary or any partnership or limited liability company controlled by the
Company. Further, the adoption of this Plan shall not be deemed to give any
Eligible Employee or any other individual any right to be selected as a
Participant or to be granted an Option.

     SECTION 8.8 Reliance on Reports. Each member of the Committee and each
member of the Board shall be fully justified in relying or acting in good faith
upon any report made by the independent public accountants of the Company and
its Subsidiaries and upon any other information furnished in connection with the
Plan by any person or persons other than the Committee or Board member. In no
event shall any person who is or shall have been a member of the Committee or of
the Board be liable for any determination made or other action taken or any
omission to act in reliance upon any such report or information or for any
action taken, including the furnishing of information, or failure to act, if in
good faith.


                                      -6-
<PAGE>   9


     SECTION 8.9 Construction. The titles and headings of the sections in the
Plan are for the convenience of reference only, and in the event of any
conflict, the text of the Plan, rather than such titles or headings, shall
control.

     SECTION 8.10 Governing Law. The Plan shall be governed by and construed in
accordance with the laws of the State of Oklahoma except as superseded by
applicable federal law.

                                   ARTICLE IX

                  ACCELERATION OF OPTIONS UPON CORPORATE EVENT

     SECTION 9.1 Procedures for Acceleration and Exercise. If the Company shall,
pursuant to action by the Board, at any time propose to dissolve or liquidate or
merge into, consolidate with, or sell or otherwise transfer all or substantially
all of its assets to another corporation and provision is not made pursuant to
the terms of such transaction for the assumption by the surviving, resulting or
acquiring corporation of outstanding Options under the Plan, or for the
substitution of new options therefor, the Committee shall cause written notice
of the proposed transaction to be given to each Participant no less than forty
days prior to the anticipated effective date of the proposed transaction, and
the Participant's Option shall become 100% vested. Prior to a date specified in
such notice, which shall be not more than ten days prior to the anticipated
effective date of the proposed transaction, each Participant shall have the
right to exercise his or her Option to purchase any or all of the Common Stock
then subject to such Option. Each Participant, by so notifying the Company in
writing, may, in exercising his or her Option, condition such exercise upon, and
provide that such exercise shall become effective immediately prior to the
consummation of the transaction, in which event such Participant need not make
payment for the Common Stock to be purchased upon exercise of such Option until
five days after receipt of written notice by the Company to such Participant
that the transaction has been consummated. If the transaction is consummated,
each Option, to the extent not previously exercised prior to the date specified
in the foregoing notice, shall terminate on the effective date such transaction
is consummated. If the transaction is abandoned, (i) any Common Stock not
purchased upon exercise of such Option shall continue to be available for
purchase in accordance with the other provisions of the Plan and (ii) to the
extent that any Option not exercised prior to such abandonment shall have vested
solely by operation of this Section 9.1, such vesting shall be deemed voided as
of the time such acceleration otherwise occurred pursuant to Section 9.1, and
the vesting schedule set forth in the Participant's Option Agreement shall be
reinstituted as of the date of such abandonment.

     SECTION 9.2 Certain Additional Payments by the Company. The Committee may,
in its sole discretion, provide in any Option Agreement for certain payments by
the Company in the event that acceleration of vesting of any Option under the
Plan is subject to the excise tax imposed by Section 4999 of the Code or any
interest or penalties with respect to such excise tax (such excise tax, interest
and penalties, collectively, the "Excise Tax"). An Option Agreement may provide
that the Participant shall be entitled to receive a payment (a "Gross-Up
Payment") in an amount such that after payment by the Participant of all taxes
(including any interest or penalties imposed with respect to such taxes),
including any Excise Tax, imposed upon the Gross-Up Payment, the Participant
retains an amount of the Gross-Up Payment equal to the Excise Tax imposed upon
such acceleration of vesting of any Option.


                                      -7-