That there Race the Sun [official site] is a fine game. You skim across abstract landscapes in a solar-powered vehicle, trying desperately to outrun the impending sunset while not smashing into the odd architecture like a ruddy great fool. It's fast and exciting. I'd recommend you pay money for it, and I'll certainly recommend you snag it for free.
You have, I believe, until about 6:30pm tomorrow to grab it. You don't even need to install it today, as long as you move quickly and register it - you can do it all in your browser, no Steam client required.
What more need I say? It's free, it's fun, and it looks like this:
Go get it.