Contra Force departs from many of the Contra gameplay conventions. The game is still a combination of over-head and side-scrolling shooting, but many changes have been made. There are four characters to choose from, each with his own arsenal of weapons. Characters can be changed during gameplay by hitting the select button, and each one has his own amount of spare lives (the game ends if one of them runs out). The player can play the game alone, with a second player or with an AI-controlled partner. The AI-controlled partner can be called upon by the player during gameplay from the sub-menu and can be assigned to cover the player's character, attack incoming enemies or mimic the player's movement. However, the AI-controlled partner only stays on-screen for five seconds and must be summoned again.
Instead of picking up individual power-up items from flying capsules or sensors, the player has a 'power selection gauge' similar to the Gradius series. The player's character find briefcases hidden in the destroyable environment, which moves the selection cursor to the next power-up. If the player dies, not only is the current weapon lost, but also the amount built up in the power meter. The initial weapon, the pistol, does not even shoot bullets the length of the screen. Overall, the game plays much slower than other Contra titles.
There are a total of five stages in the game: three side-scrolling (odd-numbered stages) and two overhead (even-numbered stages). The levels also include a good amount of destructible terrain, sometimes yielding power-up brief cases, other times just needless destruction. The stages consist of a harbor, a ship, a construction site, an airplane and the team's headquarters.