The "Build 31122013" likely refers to a specific legacy update from late 2013. While official servers for many older games can be spotty, Worms Ultimate Mayhem still maintains a presence on modern storefronts that support online play through their respective platforms.
Supports up to 4 players across 5 different modes like "Statue Defend" and "Deathmatch". download-worms-ultimate-mayhem-build-31122013-online
One of the deepest systems in the series, allowing you to build custom weapons and dress your worms in bizarre outfits. The "Build 31122013" likely refers to a specific