In case you’re new to the whole “free Steam weekend” thing, it’s not a case of “download and it’s yours forever” – it’s just free to play until the end of the weekend, when it will magically re-lock itself. Of course, it’s also 50% off, so if you actually enjoy horribly optimised and entirely phoned-in messes then you can grab it for only £19.99. This appears to coincide with a Double XP weekend, too, if that’s the sort of thing that matters to you.
This weekend also marks a Ubisoft sale on Steam, so if you fancy spending £20 on good games, you could instead pick up Rayman Origins for £6.49, or Rayman Legends for £16.24, or Splinter Cell: Blacklist for £19.49, or all sorts of other things. The Ubisoft sale is offering new deals each day, though, so I’m guessing those particular titles will be cheaper a little later on in the weekend. You may want to hold off to see if they’re picked for a further discount, as today’s Super Special Deal is the Might & Magic series.