Based on the Oscar-winning 1986 Oliver Stone war drama of the same name, Sunsoft's Platoon places the player in charge of a small group of United States soldiers deep in the heart of a Vietnamese jungle, with a series of platform, shooter, and maze challenges blocking the way back to friendly territory. The player controls one soldier at a time and the game is broken into several areas with different objectives and challenges. Armed with hand grenades and rifles, the soldiers must battle across bridges, through sewers, and into the heart of an enemy bunker.

Some enemies walk about as the player's character does, but others can be found in trees and lying flat on the ground for cover, sniping the hero from relatively protected positions. Booby traps also spell disaster with the slightest misstep. Players must keep an eye on both the soldier's ammunition supply and his morale level. Running out of bullets or grenades leaves the hero relatively defenseless against enemy attacks. Morale will drop when innocent local villagers are shot. A balance of cautious advances and quick reactions are required to guide the platoon to safety.