Back in 2008, Adam Atomic and Danny Baranowsky, two of the three masterminds behind Canabalt created a flash game called Gravity Hook originally based on a typing-tutor game called Gravity Key by Arne Niklas Jansson. After securing permission to develop an endless mouse-based version of the game, the original Gravity Hook was created in five days utilizing the beginnings of what is now the flixel framework.
A year later, Danny and Adam revisited their game and added new graphics, sound, controls, and gameplay to create Gravity Hook HD. Much like Canabalt, a free flash version is available that allows players to experience the game in its entirety, with global leaderboards reserved for the upcoming iPhone version.
If you have flash installed, you can try out Gravity Hook HD by clicking below. The game has sound, so make sure you mute your speakers before clicking if you're playing somewhere that epic soundtracks are frowned upon.
The developers aren't ready to discuss specific release dates, but hope to have Gravity Hook HD on the App Store sometime this month. We plan on spending some time at GDC with the entire Semi Secret Software crew, and might have more information on Gravity Hook HD then.