Ricochet is a multiplayer mod of the popular first-person shooter Half-Life. It was developed by Valve Software and originally released on November 1, 2000.
The portable Version contains:
Only 158MB
Playable on internet and LAN (Type sv_lan 0 to let other internet players join)
Works on all computers, no need for any admin access
About 15-20 custom maps
RicoBot included for single-player play. Type in 'addbot' in console to add a bot.