Liero is a computer game for DOS, first released by Finnish programmer Joosa Riekkinen in 1998. The game has been described as a real-time version of Worms. It has many weapons and sounds from its precursor, MoleZ. 'Liero' is Finnish for earthworm and is pronounced [lie.ro]. Later on, this game provided inspiration for the game Soldat.
Unlike most side-scrolling deathmatch games, the weapons in Liero have infinite ammo. Key factors include the reload rate of each weapon and how fast they shoot, whereas in most others include how much ammo a gun sports and how frequent more ammo for that gun can be found. Liero depends all on timing and swift maneuverability.
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 a single player mode against the game's artificial intelligence, although the game's popularity is derived mostly from the fast-paced player vs. player action it provides.
Liero is a very versatile game in terms of modification. All of its 40 weapons can be completely replaced with new ones that can be given different images and sound effects from the original set. The images of the worms themselves can be transformed into completely different characters, although their movement animations are less flexible regarding modification. The maps can be given permanent terrain other than rocks alone. Destroyable terrain can also be colored more than simply plain dirt. The AI can be upgraded or downgraded to be harder or easier. Nearly the whole game can be converted into something entirely different, except for the main aspect having to do with slaughtering another player/AI.
The weapons arsenal contains 17 weapons, of which most remain in Liero. In addition to weapons there is a ninja rope, differing from Liero's rope, in that it's significantly weaker and releases while in use. The weapon arsenal, graphics and gameplay are also more simple than those of Liero. Another difference from Liero is that MoleZ has in-game music both while it's being played and in its menus. Liero reuses most of the sounds found in MoleZ.
The game interface allow players to modify factors of the game such as which weapons in a mod are allowed, and how fast they reload. This directly affects weapon balancing. Players sometimes reduce loading time in an attempt to increase the pace of the game from the standard 100% loading time. Although 100% loading time is the standard to which all mods are balanced under, 20% loading time and below are common as well. Another very common modification is to disallow the use of some weapons, even to the point where only a single weapon is allowed. The irrefutably most common setting is the Modern Warfare mod, with all weapons disallowed except for the Mortar Launcher liked by many players for the ease in obtaining kills with the "one hit kill" mortar. Another common single weapon setting is the default Classic mod with only Rifles allowed. Differing from the original Liero, it is possible in Liero Xtreme to switch weapons and fire in such rapid succession that single shot weapons such as the Mortar Launcher or Rifle can be fired in bursts of five shots. This feature is known as comboing, and is a topic of controversy within the LieroX community.
NiL (recursive acronym for NiL Isn't Liero) is another clone of Liero, which runs on Linux and Windows and is released under the terms of the GNU General Public License. NiL is not, like Liero, limited to two players as it has support for an infinite number of players over a TCP network. It was met with considerable enthusiasm in the Linux gaming community .
The project was initiated by Flamming Frandsen in winter 1999 after he had stumbled across Liero, which he liked so much that he decided to reimplement it under Linux. He abandoned the project however five months later due to being too busy for it. NiL was then dead until the beginning of 2004 when the current maintainer of NiL, Christoph Brill, found out about the project and took over. Thereafter Daniel Schneidereit joined the project as well, but soon left. Other contributors included Nils Thuerey, Harri Liusvaara, David Hewitt and Phil Howlett.
Development however proceeded slowly as the project's source code became almost unmaintainable and NiL was lacking developers. By mid-2005 Alexander Kahl joined development, convinced Christoph to start over and re-think the whole concept of NiL, as the other Liero clone Gusanos already existed at that time. Development seems to have stopped around mid 2006.
Gusanos, Spanish for worms, is a free cross-platform clone of Liero, written in C++ using the Allegro library and the Zoidcom library. It was created by the Argentine programmer Mario “Basara” Carbajal, assisted by various other programmers over the Internet. Gusanos implements various improvements such as dynamic lights and netplay.
The latest version is 0.9c (released January 31, 2006), which is a completely rewritten version over 0.8 and is fully moddable. Already produced mods include Lightsaber Arena (Star Wars style), Doom (like the game) and 133 (a mod with old Liero weapons). In March 2005, Erik "Gliptic" Lindroos, creator stopped LOSP development to join the Gusanos team (merging the two projects into one, carrying the name of Gusanos).
Version 1.0 has been planned since the previous release, but development seems to have stopped around the end of 2006.
Gusanos is released under the GNU General Public License, although it dynamically links both the FMOD and Zoidcom libraries. Mario has expressed little interest in the licensing of Gusanos, and doesn't mind which licensing it is under.
LOSP (Liero Open Source Project) is a free clone, written in C++, based on the original code of Liero 1.33. It was coded by the Swedish programmer Erik 'Gliptic' Lindroos via reverse engineering (since the original source code was unreleased and lost).
The intention was to make the physics as close to the original game as possible—basically, a free and open source copy of Liero. The game features the same forty weapons as Liero, as well as the ninja rope.
In 2005 Erik decided to discontinue further development and joined Mario Carbajal with developing Gusanos using code and ideas from LOSP. The last version released was "Pre-beta 10" in July 2004.
Unlike what the name suggests, the source code was withheld by Gliptic until November 17, 2006, which was when it was released to the public. The source was withheld because of flaws in the code, which made it impossible to compile LOSP, as well as the incorporation of all vital LOSP code into Gusanos, which rendered LOSP obsolete.
LOSP has become further obsolete due to Gliptic's OpenLiero, an almost exact clone of Liero, which bears less glitches.
LieroAI is another clone/remake of Liero.