Worms 2: Armageddon is a sequel to the 2007 version of Worms. It adds a new 30-mission campaign, three tutorials, and five secret missions. 40 weapons are available, including returning favorites (the sheep variants and the Holy Hand Grenade), and some new additions (a Bunker Buster and the Buffalo of Lies).

Players control a team of armed worms fighting atop a 2-D randomized battlefield. Players take turns controlling one worm at a time, and can either position the worm until time runs out, or use one weapon from a selectable menu. Direct fire weapons (shotguns, Uzis) are used by the worm that selected it against whatever's nearby. Thrown weapons (grenades, bazookas) are aimed by the player and affected by ever-changing wind. Explosive weapons (airstrikes, bombs) blow holes in the terrain and drop any nearby worms into the new craters.

Most weapons have a limited number of uses per map. Each individual worm on the team has their own health meter, and will die when it reaches zero or they are knocked off the terrain and into the water. The team that loses all its worms loses the match.

Players can compete against the single-player A.I., or against each other online or off. Multiplayer features different game types (deathmatch, forts, and races), with leaderboards for each. Players also unlock customization options as they play through the single-player campaign, allowing them to create new teams with custom names, hats, voices, and attitudes.