Local machine multiplayer games

[Mincus]

Guitar Hero (not advised as the pc version is bugged like hell and costs you twelve times as much as AS)

There is the free Frets on Fire, which is essentially the same game as Guitar Hero.
Apparently it's capable of importing Guitar Hero 1 or 2 tracks, you can create your own to music you have (with a little patience). Some other sources of tracks in the FAQ section of the site. Also, there's always a-torrenting (only for tracks you already own, I would assume).

[Koen]

Worms Armageddon (get the new patches!)

Still one of the most fun games to play in hotseat mode.

[S.]

Guitar Hero (not advised as the pc version is bugged like hell and costs you twelve times as much as AS)

There is the free Frets on Fire, which is essentially the same game as Guitar Hero.
Apparently it's capable of importing Guitar Hero 1 or 2 tracks, you can create your own to music you have (with a little patience). Some other sources of tracks in the FAQ section of the site. Also, there's always a-torrenting (only for tracks you already own, I would assume).

Guitar Hero 3, Aerosmith and World Tour all have pc versions. Smash Hits and Metallica were planned too iirc, but were cancelled due to the huge failing of the other 3 guitar hero's.

Worms Armageddon (get the new patches!)

Still one of the most fun games to play in hotseat mode.

I'm playing Worms World Party atm. Too bad that online they only play shoppa, which sucks. Anyway, hotseat is great, if you have a friend/relative to play with -_-'




-Many old racegames have splitscreen mode.

[metaLsurfeR]

Blur - finally some new racing game with SplitScreen support. 

[Uupis]

I believe most TBS games have a hotseat mode.

Civ, HoMM, King's Bounty...

[blue_h3x]

Turns out both Track Mania Nations Forever and Trine both support my 8 year old game pad, rather surprising. Means I can play keys/mouse + gamepad multiplayer in those games now ^^

[Ko-Tao]

Shatter also supports local mp.

Quite the fun game, btw.