Worms: Open Warfare isn't a follow-up to the Worms series, but rather a new version made specifically for contemporary handheld consoles. Instead of keeping on with the 3D style of Worms 3D and Worms 4: Mayhem, the game goes back to its roots, featuring the classical 2D gameplay and smaller weapon set from the first Worms games.

Each player has a team of worms that has to battle it out against opponent teams in a destructible terrain, with several wacky weapons at their disposal, similar to artillery games. The player can either opt for the single-player mode, competing in custom matches or setting challenges against computer teams; or play against human opponents in hotswap or multiplayer modes. The PSP version features wireless Ad-Hoc functionality.