Question: Cyberspace is a cyberpunk role-playing game published by Iron Crown Enterprises and using a somewhat modified version of the ruleset of which science fiction role-playing game, developed by Kevin Barrett, and Terry K. Amthor?
Context: Lord of the Rings Adventure Game is a role-playing game based on the writings of J.R.R. Tolkien (specifically "The Lord of the Rings" and "The Hobbit") under license from Tolkien Enterprises.  Iron Crown Enterprises (I.C.E.) published the game until they lost the license on 22 September 1999. High Adventure Role Playing (HARP) is a fantasy role-playing game, designed by Tim Dugger & Heike A. Kubasch, and published by Iron Crown Enterprises (ICE). Metamorphosis Alpha is a science fiction role-playing game.  It was created by James M. Ward and originally produced by TSR, the publisher of "Dungeons & Dragons".  It was the first science fiction role-playing game, published in July 1976. Shadow World is a high-fantasy campaign setting situated on the fictional planet of Kulthea.  Originally produced for the Rolemaster role-playing game system, the game setting is owned by Iron Crown Enterprises (often referred to as I.C.E.).  It is currently maintained by the primary author of the setting, Terry K. Amthor of Eidolon Studio (who also holds the trademark for Shadow World, and copyrights for non-gaming fiction related to the world). Cyberspace is a cyberpunk role-playing game published by Iron Crown Enterprises and using a somewhat modified version of their "Spacemaster" ruleset. Cyberpunk, mainly known by its second edition title Cyberpunk 2020, is a cyberpunk role-playing game written by Mike Pondsmith and published by R. Talsorian Games in 1988.  Because of the release in 1990 of the second edition, set in a fictional 2020, the first edition is often now referred to as "Cyberpunk 2013", following the fictional year, 2013, in which the game was set when it was first released in 1988.  The third edition, published by R. Talsorian Games in 2005, is referred to as "Cyberpunk V3.0" and is set further along the same fictional timeline as the former editions, during the 2030s. Space Master is a science fiction role-playing game produced by Iron Crown Enterprises, written by Kevin Barrett, developed by Kevin Barrett and Terry K. Amthor. Rolemaster is a role-playing game published by Iron Crown Enterprises.  Rolemaster has come in four separate editions.  The third edition, first published in 1995, is also known as the "Rolemaster Standard System" (or RMSS for short).  "Rolemaster Fantasy Roleplaying" (or RMFRP) was first published in 1999 as a reorganized edition of RMSS, and is largely compatible with that edition.  The most recent publication of the Rolemaster rule set is "Rolemaster Classic" (RMC), a republished set of the second edition rules. Middle-earth Role Playing (MERP) is a 1984 role-playing game based on the writings of J.R.R. Tolkien (specifically "The Lord of the Rings" and "The Hobbit") under license from Tolkien Enterprises.  Iron Crown Enterprises (I.C.E.) published the game until they lost the license on 22 September 1999. Silent Death is a miniatures space battle game by Iron Crown Enterprises (ICE), based on the "Star Strike" sourcebook to the "Spacemaster" role-playing game, but with vastly simplified mechanics.  In particular, combat is fast and lethal, and so chances of crewman death or ship destruction are frighteningly high in a single battle.  This makes "Silent Death" much more suitable as a standalone game than as a space-combat addition to a role-playing game.
Answer: Spacemaster