Assault: Retribution is a 3D run and gun platform game. Its story takes place in the year 2198. Arcadia, a world far away from Earth, is under attack by aliens. As members of the Arcadia Defense Force, the player takes part in the fight against the invaders.
Featuring 3D graphics, the game's perspective varies from side scrolling to top down. There are 4 weapons available to each character, though the differences are mostly cosmetic (a weak gun with wide spread, a stronger but slightly slower gun, a homing weapon, and a powerful BFG). As the character picks up a Gun item, the character's next tier gun slot is filled. Each gun can be upgraded three times, which increases the number of shots fired per trigger pull, but also increases energy drain. Energy can be recovered by picking up the appropriate item, as can health. It is also possible to store health or energy for later use (though each character has only one item slot). Other pick ups includes an invulnerable energy sphere (can't be stored), lighting barrier and bonus lives. Besides the usual movement and shooting, the characters can also aim up, down at various angles and have a 'strafe/ side step' move.
There are seven action packed levels. Multiplayer is possible in two-player co-op mode.