Liero is a computer game for DOS. It was created by the Finnish programmer Joosa Riekkinen in 1998. The game is often described as real-time (i.e. not turn-based), Worms, or 2D Quake III. It has many weapons and sounds from it's precursor MoleZ. 'Liero' is the Finnish word for worm.
In Liero two worms fight each other to death for score (or frags) using a wide variety of weapons in a two-dimensional map. Certain parts of the terrain may be dug or destroyed by explosions. In addition to the weaponry, each player has a ninja rope which can be used to move faster through the map.
The gameplay mode can be deathmatch, game of tag or capture the flag. It can be played by two human players simultaneously in split screen or in single player mode against the game's AI, although the game's popularity is derived mostly from the fast-paced human vs. human action it provides.
Its last release was version 1.33. However, Liero is currently an abandoned project and due to the closed source nature of this software no new versions have made it to the light since. Despite of this, and against the author's will, the Liero community has been distributing several altered (or hacked) versions of the game through the Internet known as 'mods' or 'total conversions' (TCs).
The Liero community has grown widely since the comedown of the original Liero, producing many clones of the game for different platforms, incorporating innovative features not present in Riekkinen's game.