For this weekend only, Semi Secret Software (Canabalt) is giving away its very, very addictive iPhone/iPod Touch/iPad game Gravity Hook HD. There's already a free online version you can play, but now you don't have to pay to take it around with you.

Gravity Hook HD is a simple game in which you ascend a mine by tapping and pulling yourself toward floating orbs, avoiding mines scattered around the stage while using your momentum to reach higher orbs.

It might sound simple, but the game really has that "just one more try" aspect to it (which you'll repeat for the next hour), and it features an awesome soundtrack by Danny Baranowsky.