I learned that fact after buying it and I never installed it. I think it was like 2.99$ when I bought it and not sure I will ever install it. I hate such requirements.
I was pretty peeved. Not sure if I missed the requirement on the Steam page or it wasn't there, probably the former. If I didn't have XBL I would have done what you did.
The game is pretty fun. It's apparently almost exactly Flatout 2, which I never played. It's a huge step up over Flatout 1, though, and avoids most of what I hated about that game (which I dug a ton, but had some serious flaws.) I read some reviews that complain about it being hard, but honestly I'm finding it very easy to get the gold on every single racing event (and I'm playing with a keyboard.) Still satisfying.
One of the better $2.99 Steam sale purchases I've made. Stupid fun, but a lot of it. Most of the other $2.99 purchases I've made have either been rebuying games I have on CD or, like this, taking a risk on an older game which I often never even install. Speaking of, time to finally give Mount & Blade a go.