A platform shoot-em-up hybrid from Sega for one to four players, selected from either Joe (yellow), Mary (red), Lee (blue) and Edgar (green). The action takes place over a number of sideways scrolling levels, the bulk of which consist of straightforward platform action. On some levels, however, there are jet packs for the players to collect, and the gameplay's emphasis switched to that of a standard, sideways scrolling shoot-em-up. The object of the game is to destroy an army of robots that have taken over an Earth colony satellite station. Each level has a boss character that must be destroyed. Upon its death it releases a door key that must be used to exit the level. Weapon and character power-ups can be collected to aid players in their task. Due to its potential for four-player shoot-em-up gameplay, Quartet's gameplay feels vaguely similar to (though by no means as accomplished as) Atari's 1985 classic, Gauntlet.