"Ricochet is a multiplayer mod of the popular first-person shooter Half-Life. It was developed by Valve Corporation and originally released on November 1, 2000. The 18.104.22.168 patch of the game was later released on June 12, 2002. It is an official mod, and is available through Steam for purchase; however, it is free for those who purchased the retail version of Half-Life prior to the release of Steam.
Ricochet is a deathmatch game notable for its apparent simplicity, inspired by arcade games and platform games in both concept and design. One of its main sources of inspiration is the film Tron in which a similar game is played. Players jump between neon-lit platforms suspended above an abyss, and shoot disks at one another, trying to push the opponent off the platform and into the depths.
There are also horizontal barriers which the disks can bounce off (hence the name Ricochet); a direct hit resulting in a fall scores 1 point, a single-bounced hit scores 2 points, double-bounced 3 points, and so on. Ricochet also features a second attack (done by the alternate fire key) which cuts off the head of your opponent. The decapitation attack (as it is called) uses all three of your discs, but recharges all of them at once quickly.
Unlike in other Half-Life mods, the number of player deaths is not shown on the scoreboard, only the number of kill points. The aiming is effectively two-dimensional, and the movement is reduced to automated jumping between the platforms, though some maneuvering can be performed in mid-air by advanced players.
Three maps come with the mod, two for deathmatch and one for duel combat. Maps for Ricochet use the prefix "rc". Custom Ricochet maps are rare, but a few can be found."
Source: Wikipedia, "Ricochet (2000 video game)", available under the CC-BY-SA License.