Taking advantage of the technology provided by the Super NES, the graphics in Contra III improved upon the NES versions of the first two installments, bringing it closer to the quality of their arcade counterparts. The level design is more complex, and provides more opportunity for interaction. For instance, players can grab on to poles or ceilings and navigate them in a monkey bar fashion, climb walls and ladders, destroy buildings and scenery, and commandeer tanks.
New styles of levels in The Alien Wars involve motorcycle chases, riding on missiles, and two Mode 7 enabled top-view levels. Players can carry and switch between two weapons at any time, only losing the one they are currently using if they die. They can also fire these two weapons simultaneously in a spin-jump circular fire pattern that hit enemies on all sides: however, being hit while doing so results in the player losing both of their weapons. The player can also lock their character’s mobility, allowing the player to shoot at all eight possible directions (including downwards and at angles) without moving or jumping.
There are three levels of difficulty in the game – Easy, Normal, and Hard. Each increase in difficulty setting also alters several aspects of the game. For example, enemy bosses, when fought on harder difficulties, will have new attacks or modifications to their pre-existing attacks patterns. Also, some situations in the game, such as flying in the air on missiles, become more difficult, as the missiles will travel much faster on higher difficulties. In addition, some objects and boss weak points that were destructible on easier difficulty levels will become indestructible on Normal or Hard mode.
If the player completes the game on Easy or Normal, then they will start at the very first stage on the next difficulty with their current weapon configuration, lives, and score intact. On the Hard setting, the final boss will have an additional form that the player must defeat as they escape from the Alien Lair. After defeating this form, the true ending will be shown, followed by the credits and then the player’s final score.