The Action Gamemaster was a vaporware product that is perhaps the single greatest example of the hubris evinced by Active Enterprises, a small manufacturer of unlicensed Nintendo Entertainment System games.

Active already had grandiose plans for itself — it was marketing its first commercial release, the Action 52 multicart, for both the NES and Sega Genesis, with plans to port it to the Super NES, and it was also trying to sell its signature characters, the Cheetahmen, as a line of toys, a television cartoon, and a series of video games. Despite the fact that Action 52 stands alone as one of the buggiest, most unplayable games ever made for commercial release, Active was undaunted, and announced at the 1994 CES its intentions to manufacture and produce the Action Gamemaster.

The Action Gamemaster, as planned, was to have been a portable game system in the sense of Nintendo's Game Boy and the Atari Lynx, but with much greater aspirations. It would have featured compatibility with NES, Genesis and Super NES cartridge games, as well as CD-ROM games, via adapters. This was in addition to games written exclusively for the Action Gamemaster. (One such game, Cheetahmen III, was announced at the CES show, but neither it nor the Action Gamemaster were actually on display.) Other features included a 3.2" color LCD screen, TV tuner, built-in battery charger, and a cigarette-lighter adapter for cars.

Existing concept art for the Action Gamemaster reveals a system shaped roughly like a flight yoke , with a directional pad on the left side, an action-button diamond on the right, unidentified function keys on the large central area, and the LCD screen on a bevel facing the player. There is little that can be used as a reference as to the relative size of this system, nor are any weight or power-requirement statistics available at this time.

Despite the CES announcement, it appears little to no work was actually done on the Action Gamemaster by the time Active ceased its video game operations in 1994. It is generally believed that the system, had it been realized, would have proven far too bulky and expensive to be practical (a projected retail price of around $500 USD was being suggested at the time).