THQ has made the Red Faction: Guerrilla single-player demo available to Xbox Live and PlayStation Network users in Europe who register on its website.
There are a limited amount of keys available there, which can be redeemed by going onto your preferred service, typing them in, realising you've put "8" instead of "B" a few times, changing it, eventually getting it right, and then downloading.
As for what you will be able to play, you can watch yours truly doing just that in last week's Red Faction: Guerrilla single-player demo walkthrough videos, but here's a summary: you are Alec Mason, you must go and get a walker, and you can smash lots of things to pieces on the way.
The demo isn't very long, but it does give you plenty of chances to experiment with the Geo-Mod 2.0 destruction technology that lives at the heart of all Guerrilla's visual excesses. You can smash up a building using a wrench, or switch to remote-trigger explosives to line up more elaborate demolitions.
The full game is out on 12th June for all formats.