If you've got a decent gaming PC and you haven't tried Hawken, you really should give it a try. The free-to-play online shooter captures the atmosphere of a gigantic, hulking death machine in a way that doesn't have an equal, and the first-person perspective and customizable mechs make ita nice tribute to the old Mech Warrior series. And if you've already tried it and liked it, NVIDIA has a promotional live wallpaper that's right up your rusted, diesel-splattered alley.
The Hawken Live Wallpaper is pretty similar to NVIDIA's previous freebies for Skyrim and Mass Effect 3. There are two or three horizontal planes of sprites, some special effects, and a little animation to spice things up.