Thanks for all the examples

Lol I meant PC games that were only made for the PC in mind, my bad for my poor phrasing. PC games that allow for split screens usually originated from the console side or was made concurrently with the console releases.
Heh, Zyll was a two player split-screen game back during the DOS days.:)
Tom Clancy's Rainbow Six had split-screen support, and wasn't introduced on consoles until over a full year later. Serious Sam was ported over from the PC to the XBOX only because of its popularity on the PC. They're out there, although it's kind of hard to find a game these days that isn't available on multiple platforms (short of it being an "exclusive").
Hotseat (which is not split-screen, but rather multiple players taking turns at the keyboard) was very popular in early PC gaming. But that's more for games that are completely turn-based.