X-Space '92 mini-game. When on level 6, Madness, use a computer disk found in the level on a PC to play the X-Space '92 mini game. Then you can access the mini-game if you go to the "Applications" sub-menu while pausing the game.
Earth Impact mini-game. When on level 8, Reliance, go into the games room and find a fully-operational Earth Impact mini game. Then you can access the mini-game if you go to the "Applications" sub-menu while pausing the game.