One of the nicer surprises from the holiday release frenzy late last year was Robot Invader‘s Wind-Up Knight [Free], a game we gave 5 stars in our review. Wind-Up Knight is an auto-running puzzle platformer which has you playing as a tiny knight who is mindlessly charging through each fiendishly-designed level on his own, with the task of avoiding hazards in order to survive to the end of a level left up to you. You do this by jumping, rolling, shielding, and attacking anything that gets in your way.

Wind-Up Knight requires impeccable precision and loads of patience, as to fully maximize the rewards in each and every level it will take countless deaths and retries. It’s that good kind of difficulty though, the kind that makes you want to keep coming back until you get that perfect run.

So yeah, Wind-Up Knight is pretty darn good. Another thing that’s pretty darn good is that you can now get the game for free on the App Store. If you feel guilty getting such a quality title for free, then there’s always some in-app purchase items you could splurge on to ease your conscience a bit. Although, with this latest update the items in the game’s Armory are now discounted, which means any in-game currency you get through IAP will stretch even further. I guess you’re stuck feeling at least a little bit guilty, then. Sorry.

Wind-Up Knight‘s levels are split into 4 books, the first being included for free. You can unlock additional books by using the in-game currency, which can be bought in various IAP packs or earned through play, or you can just pay a flat $1.99 to unlock each book. If you owned the original paid version of the game, then all books should be automatically unlocked, provided you have previously played through at least 1 level before updating.

The update also includes some minor tweaks such as social network integration, screen rotation support, and improved interface and gameplay flow. There’s definitely no reason not to check out Wind-Up Knight now that it’s free, so what are you waiting for?