Halo: Chronicles (Xbox 360) – Lord of the Rings and Meet the Feebles film director Peter Jackson and his company Wingnut Interactive were working on a Halo game that was meant to be episodic. But, like everything Halo related that Jackson gets his hands on (he was producing the Halo film), it was canceled. It looks like Halo 4 may be picking up the episodic idea, however, with Spartan Ops.

Halo MMO (Xbox 360)  – Ensemble Studios, the developers that released Halo Wars, were working on a Halo MMO, but it seems like they weren't able to get very far. After the release of Halo Wars, Ensemble was disbanded buy Microsoft.

Heavenly Sword 2 (PS3) – Martin Binfield, the animation team lead for the cutscenes of the original Heavenly Sword, posted his resume online and apparently Heavenly Sword 2 began development, but was canceled, presumably in favor of focusing on Enslaved. Heavenly Sword had a pretty succinct ending, a rarity in the world of video game narrative, so it’s not too disappointing that the game was shelved. Plus, Enslaved was pretty sweet.