Share The Pain is a free standalone multiplayer version of Postal 2 (which if you haven't played is essentially Grand Theft Auto as an FPS, only much bloodier and with even less moral values than GTA) which you can download right here at absolutely no cost.

It's pretty fast-paced when there's a lot of players in a server, with plenty of fun weapons ranging from the standard pistols, assault rifles, and shotguns, to the more exotic types, like sledgehammers, throwing scissors, napalm canister launchers, and cow heads filled with anthrax. Sound like fun? It is.

The download clocks in at just under 600mb, and the full game features 14 maps, 25 different characters, 11 weapons, and 4 different online modes- not bad for something that's completely free :u Plus, there are over 80 official user-made maps that you'll automatically download whenever you enter a server using them. Custom mods that introduce new weapons can lengthen the novelty of the experience even more.

Even though it's pretty old and outdated by today's standards, there's about a hundred regular players, and maybe 30-40 playing at a given time on the servers, so it's usually not too hard to find somebody to slay. I'll be starting a channel on the IRC: #postal2stp, which you can use to find people from TB to play with and whatnot.

Ahh.. Good ol' Postal 2.
Certainly a great game.