Super Crate Box was worth the cost of admission at $0.99, and for today, it's free for iOS in the App Store. It's a super challenging arcade game that requires you to collect crates with weapons to rid the world of bad guys, and it's loaded with fun retro graphics and music (check out our impressions of the game here). The game is already free on Steam, and was brought to PlayStation Mobile earlier this month by a fan. There's no reason to skip a great game when it's free, so head on over to the App Store to grab it before time runs out.