<PAGE>   1
                                                                   EXHIBIT 10(O)



                          FIRST AMENDMENT TO AGREEMENT

      This First Amendment entered into on December 23, 1998, to that certain
Agreement (the "Agreement") made November 6, 1998, by and between The Sands
Regent, a Nevada corporation (the "Seller") and Terry W. Green and Joel R.
Carter, Sr., (the "Purchasers") and Gulfside Casino Partnership d/b/a Copa
Casino ("Gulfside Partnership").

      WHEREAS, on November 6, 1998, the parties entered into the Agreement; and
now desire to amend certain provisions of said Agreement.

      NOW, THEREFORE, for and in consideration of the Mutual Covenants contained
herein, and other good and valuable consideration the parties AGREE:

      1.    Paragraph 4 of the Agreement shall be amended to the extent that
            the existing Ship Mortgages which secure certain debts and
            obligations owed by Gulfside Partnership to Seller and to
            Patrician, Inc. shall not be canceled or released but that said
            Ship Mortgages will be amended to secure the $8,000,000.00
            indebtedness described in the Agreement and in the Promissory
            Note attached thereto; provided that an undivided 50% interest in
            the Ship Mortgage to The Sands Regent shall be assigned by Seller
            to Purchasers and the Ship Mortgage to Patrician, Inc. shall be
            assigned to Seller and to Purchasers.

      2.    Paragraph 5(a) of the Agreement shall be amended to provide that
            Seller shall waive the condition that the Order of the Bankruptcy
            Court shall have become final and not appealed or stayed pending an
            appeal.

      3.    Paragraph 5(c) of the Agreement shall be amended to provide that the
            approval of the Mississippi Slate Port Authority shall be deemed
            complete upon the approval of a Resolution in the form attached as
            Exhibit "A".

      4.    That subsequent to the closing of the sale described in the
            Agreement the Purchasers shall cooperate with and permit Seller to
            continue to prepare and update the books and records of Gulfside
            Partnership, Patrician, Artemis and GCI through December 31, 1998,
            to include both financial statements and tax basis calculations.

      5.    Purchasers shall cause Gulfside Partnership to retain Deloitte and
            Touche to


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            prepare the transition year tax returns for Gulfside Partnership,
            Patrician, Artemis and GCI.

      6.    Purchasers shall cooperate and shall cause Gulfside Casino
            Partnership to cooperate with Seller in allowing Deloitte & Touche
            to perform certain audit procedures deemed necessary for The Sands
            Regent's audited financial statements.

      7.    That closing of the sale shall be deemed effective as of the close
            of the business day December 23, 1998.

      8.    Paragraph 7(6) shall be amended to provide that Seller has disclosed
            to Purchasers additional liens as shown by a UCC Search dated
            December 11, 1998 and Purchasers agree to close the sale with said
            liens in place.

      9.    Paragraph 3(D) shall be amended to provide that the $500,000.00
            shall be wire transferred to an attorney's trust account and paid to
            Escrow Agent.

      10.   Seller and Purchasers agree and stipulate that additional documents
            are required to be delivered and executed to close the transaction
            and the parties hereby agree to execute and deliver such other
            documents as may be necessary to close the transaction contemplated
            by the Agreement.

      IN WITNESS WHEREOF, the parties have duly executed this First Amendment to
that certain Agreement dated November 6, 1998.


                                       THE SANDS REGENT
DATED: 12/23/, 1998                    BY: /s/ Ferenc B. Szony
                                           -------------------------------------
                                               PRESIDENT

                                       GULFSIDE CASINO PARTNERSHIP D/B/A
                                       COPA CASINO, a Mississippi General
                                       Partnership

                                       BY:   GULFSIDE CASINO, INC.,
                                             It's General Partner

DATED: 12/23, 1998                     BY: /s/ DAVID R. WOOD
                                           -------------------------------------
                                           Vice President of Gulfside
                                           Casino, Inc.


                                       TERRY W. GREEN

DATED: 12/23, 1998                     /s/ TERRY W. GREEN
                                       -----------------------------------------


                                       JOEL R. CARTER, SR.

DATED: 12/23, 1998                     /s/ JOEL R. CARTER, SR.
                                       -----------------------------------------


<PAGE>   3

                                 PROMISSORY NOTE

$8,000,000.00                                                      Dec. 23, 1998
                                                           Gulfport, Mississippi

      FOR VALUE RECEIVED, as more particularly set forth in the Agreement and
Royalty Agreement of even date herewith, the receipt and sufficiency of all of
which is hereby acknowledged, GULFSIDE CASINO PARTNERSHIP D/B/A COPA CASINO, a
Mississippi General Partnership, ("Maker") promises to pay to the order of THE
SANDS REGENT, a Nevada corporation, ("Payee") or HOLDER, at 345 North Arlington
Avenue, Reno, Nevada 89501, or such other place as may be designated in writing,
the principal sum of $8,000,000.00 without interest in installments as follows:

      Beginning on the 10th day of January, 1999 and continuing on the 10th day
of each succeeding month thereafter until this Note shall be paid in full, in
accordance with the terms of the Agreement and the Royalty Agreement, Maker
shall pay to Payee a sum equal to (i) 2% of the monthly Gross Gaming Revenue of
the Gulfside Partnership or any successor to Gulfside Partnership or to its
interest in the Copa Casino as defined in that certain Agreement and Royalty
Agreement of even date herewith by and between The Sands Regent and Gulfside
Partnership, or (ii) $15,000.00 in cash, whichever is greater.

      The Makers, endorsers, sureties, guarantors and all other persons who may
become liable for this Note, each severally waive demand, presentment, protest
of any kind and notice of non-payment of this Note except as expressly provided
below. Maker shall, at its option, have the right to prepay this Note without
penalty. This Note is secured by a Security Agreement and UCC Financing
Statements of even date herewith.

      This Note is issued pursuant to the Agreement and the Royalty Agreement of
even date. In case an event of default as described in the Agreement shall
occur, Payee shall give Maker three (3) days notice by facsimile of said default
and if said default shall continue thereafter, then, without further notice or
demand, Payee may declare the entire unpaid principal balance at once due and
payable and may invoke all remedies permitted by law or the Agreement or Royalty
Agreement.

      In the event of default in repayment of this Note, Maker agrees to pay all
costs, including a reasonable attorney's fee, of enforcing payment and
collection of this Note.

      This Promissory Note shall be construed in accordance with the laws of
Mississippi.

      Dated: December 23, 1998.


ATTEST:                                GULFSIDE CASINO PARTNERSHIP D/B/A
                                       COPA CASINO, a Mississippi general
                                       partnership

                                       By: Gulfside Casino, Inc.,
                                           Its General Partner

/s/ FERENC B. SZONY                    By: /s/ DAVID R. WOOD
---------------------------------          -------------------------------------
                                           Vice-President of Gulfside
                                           Casino, Inc.

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              GUARANTEE OF PAYMENT AND COLLECTION

      The undersigned, Gulfside Casino, Inc., Patrician, Inc., and Artemis,
Inc., hereby jointly and severally guarantee payment and collection of the above
and foregoing Installment Promissory Note in the principal amount of
$8,000,000.00.


      Dated: December 23, 1998.

                                       GULFSIDE CASINO, INC.


                                       BY: /s/ DAVID R. WOOD
                                           -------------------------------------

                                       PATRICIAN, INC.

                                       BY: /s/ DAVID R. WOOD
                                           -------------------------------------

                                       ARTEMIS, INC.

                                       BY: /s/ DAVID R. WOOD
                                           -------------------------------------



<PAGE>   5

                                ROYALTY AGREEMENT

      THIS ROYALTY AGREEMENT (the "Royalty Agreement") is entered into as of
this the 23 day of December, 1998 (the "Effective Date"), by and among The Sands
Regent, a Nevada corporation ("Sands Regent") and Gulfside Casino Partnership
d/b/a Copa Casino, a Mississippi General Partnership ("GCP").

                                    RECITALS

      WHEREAS,  on  even  date  herewith,  Sands  Regent  entered  into  an
Agreement  (the  "Agreement")  with  Terry W.  Green and Joel R.  Carter,  Sr.
(collectively,  the "Purchasers") pursuant to which Sands Regent sold its 100%
interest in each of the three general partners of GCP to the Purchasers; and

      WHEREAS, pursuant to the Agreement, the Purchasers agreed to cause GCP to
enter into a Royalty Agreement with Sands Regent, and Sands Regent agreed to
enter into a Royalty Agreement with GCP, on the terms set forth herein; and

      WHEREAS, the Royalty Payments hereunder are for purposes of the repayment
of certain indebtedness as described in the Agreement and a Promissory Note of
even date therewith;

      NOW, THEREFORE, in consideration of the promises, covenants, agreements
and conditions contained in this Royalty Agreement, the Parties AGREE:

                                    AGREEMENT

      1.    Definitions.  As used in this Agreement,  the following terms will
have the respective meanings indicated below:

            1.1 "Gross Gaming Revenue" shall mean Gross Revenue Computations as
defined in the Regulations of the Mississippi Gaming Commission, as such
Regulations may be amended from time to time.

            1.2 "Royalty Payments" shall mean those sums that are to be paid to
Sands Regent pursuant to Section 2 below.


            1.3 "Successor Entity" shall mean any person(s) or legal entity
which directly or indirectly by sale, merger, consolidation, operation of law
or otherwise, shall acquire or otherwise succeed to a controlling or majority
ownership interest in the business and/or assets of the Gulfside Partnership
d/b/a Copa Casino whether such casino remains at its current location or is
relocated or whether the current facilities are replaced, augmented or otherwise
modified.



                                  EXHIBIT "B"


<PAGE>   6
      2. Royalties.

            2.1 Royalty Amount. Beginning January 10, 1999 and continuing on or
before the tenth (10th) day of each calendar month thereafter, GCP or any
Successor Entity, for so long as they are engaged in the gaming business, shall
pay to Sands Regent an aggregate Royalty Payment equal to the greater of (i) two
percent (2%) of the Gross Gaming Revenue for the immediately preceding calendar
month or (ii) $15,000 in cash; provided, however, that the amount of such
Royalty Payment with respect to a partial month shall be pro rated as
appropriate; and provided further, that the aggregate amount of Royalty Payments
paid hereunder shall not exceed $8,000,000 (the "Maximum Royalty Payment).

            2.2 Payment of Royalties. All Royalty Payments shall be paid by
electronic funds transfer effective on or before the date payment is due to such
bank account as from time to time may be specified by Sands Regent. The Royalty
Payments are not refundable or subject to offset of any amount due or claimed to
be due from The Sands Regent to GCP, any Successor Entity or the Purchasers.
Each monthly Royalty Payment shall be accompanied by a statement (a "Royalty
Statement") signed by the Chairman, President or Chief Financial Officer of GCP
or its Successor Entity attesting to the accuracy of the Gross Gaming Revenue
from which each such Royalty Payment was calculated and shall include copies of
the related Weekly Reports of Gaming Revenue and Monthly Gaming Reconciliation
Return filed with the Mississippi Gaming Commission along with any further
detailed reconciliations necessary to reflect Gross Gaming Revenue.

            2.3 Failure to Pay. In the event that GCP or any Successor Entity
shall fail to pay a required Royalty Payment or fail to deliver the Royalty
Statement within ten (10) days after such Royalty Payment is due and payable
then such unpaid Royalty Payment shall accrue interest at the rate of twelve
percent (12%) per annum until paid. The accrual and payment of such interest
shall not effect or constitute a waiver of any other rights or remedies Sands
Regent may have as a result of such late payment or nonpayment.

            2.4 Security. The Royalty Payments due Sands Regent hereunder are
secured under that certain Security Agreement between Sands Regent and GCP of
even date herewith.

      3. Inspection of Records. Sands Regent or its designee shall have the
right upon reasonable notice from time to time, to have its representatives
enter the premises of GCP and each Successor Entity or any other location or
facility which any of GCP or a Successor Entity may use in connection with the
operation of its business for the purpose of inspecting the books and records
of account and condition and operation of GCP's or the Successor Entity's
business. Sands Regents' representatives shall have the right at all times
during normal business hours to inspect and reproduce the records, books, tax
returns and reports of GCP and any Successor Entity at the expense of The Sands
Regent. All such books, records and tax returns shall be maintained at the
premises of GCP or such other place as may be agreed upon by the parties in
writing. If any inspection reveals that a Royalty Statement submitted to Sands
Regent understates Gross Gaming Revenues, then GCP or the Successor Entity shall



                                       2
<PAGE>   7
immediately pay Sands Regent all additional amounts owing by reason of the
understatement of Gross Gaming Revenue previously reported, together with
interest thereon in accordance with Section 2.3. In the event that any Royalty
Statement understates Gross Gaming Revenue by more than five percent (5%), GCP
or the Successor Entity, as applicable, shall, in addition to the making the
payment provided for above, make an additional Royalty Payment to Sands Regent
equal to ten percent (10%) of the understated revenue and shall reimburse Sands
Regent for any and all expenses incurred in connection with such inspection,
including, but not limited to, Sands Regents' actual accounting and legal fees.
Such payment shall be made without prejudice to any other rights or remedies
which Sands Regent may have under this Agreement or otherwise.

      4. Assignment. GCP shall not (i) sell, assign or transfer its obligations
under this Royalty Agreement including, but not limited to, its obligations to
make Royalty Payments to Sands Regent hereunder, except in compliance with
paragraph 6 "Successors" of that certain Agreement of even date herewith; or
(ii) take any action to circumvent or avoid its obligation to make Royalty
Payments hereunder.

      5. Governing Law and Jurisdiction. This Agreement shall be governed by
and interpreted in accordance with the laws of Mississippi. Each of the parties
hereto consents to said jurisdiction for enforcement of this Royalty Agreement.

      6. Attorneys' Fees. In the event a dispute arises with respect to this
Royalty Agreement, the party prevailing in such dispute shall be entitled to
recover all expenses, including, without limitation, reasonable attorneys' fees
and expenses incurred in ascertaining such party's rights, in preparing to
enforce, or in enforcing such party's rights under this Royalty Agreement,
whether or not it was necessary for such party to institute suit.

      7. Complete Agreement of the Parties. This Royalty Agreement and the
Agreement supersede any and all other agreements whether oral or in writing,
between the parties with respect to the subject matter hereof and contain all of
the covenants and agreements between the parties with respect to such matter in
any manner whatsoever. Each party to this Royalty Agreement acknowledges that no
representations, inducements, promises or agreements, oral or otherwise, have
been made by any party, or anyone herein, and that no other agreement, statement
or promise not contained in this Royalty Agreement shall be valid or binding.
This Royalty Agreement may be changed or amended only by an amendment in writing
signed by all of the parties or their respective successors-in-interest.

      8. Binding. This Royalty Agreement shall be binding upon and inure to the
benefit of the successors and assigns of the respective parties.

      9. Failure to Object Not a Waiver. The failure of either party to this
Royalty Agreement to object to, or to take affirmative action with respect to,
any conduct of the other which is in violation of the terms of this Royalty
Agreement, shall not be construed as a waiver of the violation or breach or of
any future violation, breach or wrongful conduct.



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<PAGE>   8

      10. Unenforceable Terms. Any provision hereof prohibited by law or
unenforceable under any applicable law of any jurisdiction shall as to such
jurisdiction be ineffective without affecting any other provisions of this
Royalty Agreement. To the full extent, however, that the provisions of such
applicable law may be waived, they are hereby waived to the end that this
agreement be deemed to be a valid and binding agreement enforceable in
accordance with its terms.

      11. Execution in Counterparts. This Royalty Agreement may be executed in
several counterparts and, when so executed, shall constitute one agreement
binding on all the parties, notwithstanding that all the parties are not
signatory to the original and same counterpart.

      12. Further Assurance. From time to time, each party will execute and
deliver such further instruments and will take such other action as any other
party may reasonably request in order to discharge and perform their obligations
and agreements hereunder and to give effect to the intentions express in this
Royalty Agreement.

      IN WITNESS WHEREOF, the Parties hereto have duly executed this Royalty
Agreement.


DATED: 12/23/98                        THE SANDS REGENT, a Nevada corporation

                                       By: /s/ FERENC B. SZONY
                                           -------------------------------------
                                           President


DATED: 12/23/98                        THE GULFSIDE CASINO PARTNERSHIP D/B/A
                                       COPA CASINO, a Mississippi general
                                       partnership

                                       By: Gulfside Casino, Inc., Its General
                                           Partner

                                       By: /s/ DAVID R. WOOD
                                           -------------------------------------
                                           Vice President of Gulfside
                                           Casino, Inc.



                                       4
<PAGE>   9
STATE OF Mississippi
COUNTY OF Harrison

      PERSONALLY came and appeared before me, the undersigned authority in and
for the aforesaid County and State, the within named Ferenc Szony who
acknowledged to me that he is the President of THE SANDS REGENT, a Nevada
corporation, and that for and on behalf of said corporation and as its act and
deed, he signed, executed and delivered the above and foregoing Agreement on the
day and year therein mentioned and for the purposes therein stated, after having
first duly read and understood said Agreement and having been duly authorized by
said corporation so to do.

      GIVEN UNDER MY HAND AND SEAL OF OFFICE, this the 23rd day of December
1998.


                                       /s/ LISA L. PARKER
                                       -----------------------------------------
                                       NOTARY PUBLIC


My Commission Expires:

January 5, 2000


STATE 0F Mississippi
COUNTY OF Harrison

      PERSONALLY came and appeared before me, the undersigned authority in and
for the aforesaid County and State, the within named Dave Wood who acknowledged
to me that he is the Vice President of GULFSIDE CASINO, INC., A Mississippi
corporation and a General Partner of GULFSIDE CASINO PARTNERSHIP D/B/A COPA
CASINO, a Mississippi general partnership, and that for and on behalf of said
corporation and as its act and deed on behalf of said partnership as General
Partner, he signed, executed and delivered the above and foregoing Agreement on
the day and year therein mentioned and for the purposes therein stated, after
having first duly read and understood said Agreement and having been duly
authorized by said corporation so to do.

      GIVEN UNDER MY HAND AND SEAL OF OFFICE, this the 23rd day of December
1998.


                                       /s/ LISA L. PARKER
                                       -----------------------------------------
                                       NOTARY PUBLIC


My Commission Expires:

January 5, 2000



                                       5