You can grab hold of some nostalgia for the next few hours by snagging a free copy of Abe's Oddysee through Steam. Note: This is the old version of the game, not the remake (Oddworld: New 'n' Tasty) released earlier this year. I guess they hope you'll try the old one and either hate it or love it enough to want to buy the remastered version.
Act fast, though. Like most freebie Steam deals, this offer is only valid until 10 AM Pacific Time tomorrow, a.k.a. September 24. Log into your Steam account and go here between now and then, add Abe's Oddysee to your account, and you'll own it forever. Simple.
The rest of the Oddworld games are also on sale, if you're interested, as well as the aforementioned New 'n' Tasty remake.
Hayden Dingman