Cannon Fodder is a military-themed action game with strategy and shoot 'em up elements. The player controls a small squad of up to five soldiers. These soldiers are armed with machine guns which kill enemy infantry with a single round. The player's troops are similarly fragile, and while they possess superior fire-power at the game's outset, the enemy infantry becomes more powerful as the game progresses. As well as foot soldiers, the antagonists include vehicles such as Jeeps, tanks and helicopters as well as missile-armed turrets. The player must also destroy buildings which spawn enemy soldiers. For these targets, which are invulnerable to machine gun fire, the player must utilise secondary, explosive weaponry: grenades and rockets. Ammunition for these weapons is limited and the player must find supply crates to replenish his troops. Wasting these weapons can potentially result in the player not having enough to fulfil the mission objectives. The player can opt to shoot crates - destroying enemy troops and buildings in the ensuing explosion - at less risk to his soldiers than retrieving them, but again at a greater risk of depleting ammunition.
The player proceeds through 23 missions divided into several levels each, making 72 levels in all. There are various settings including jungle, snow and desert, some with unique terrain features and vehicles such as igloos and snowmobiles. The player must also contend with rivers (crossing which soldiers are slowed and cannot fire) and quicksand as well as mines and other booby traps. In addition to shooting action, the game features strategy elements and employs a point-and-click control system more common to strategy than action games. As the player's troops are heavily outnumbered and easily killed, he must use caution, as well as careful planning and positioning. To this end, he can split the squad into smaller units to take up separate positions or risk fewer soldiers when moving into dangerous areas.