Sven Co-op 4.8

Sven Co-op is a cooperative mod for Half-Life in which players work as a team to kill computer-controlled monsters, solve puzzles and complete various objectives (listed in the MOTD). The game is completely free; to play it you need an installed Half-Life client.

The player controls are the same as in Half-Life. Some Half-Life levels have been modified in Sven Coop to make them even more playable in co-op mode. The levels in Sven Coop are split into missions that are separate from one another. Most missions consist of several maps, or even series of maps. The main task in these missions is to reach a specific goal -- scoring the most points is not what matters. The map's scenario and where it takes place are entirely up to the map's author.