4. Neill Blomkamp's Halo / Gore Verbinski's Bioshock
Descriptions: I highly doubt you need the synopsis to these properties, but in case you do Halo is story of humankind versus the alien Covenant race, who are bent on destroying the universe by activating the Halo stations across that very expanse. It's up to Master Chief to defend the Universe against all who oppose. Bioshock, on the other hand, is a macabre twist on a Randian society under the sea. Obsessed with perfection and personal propriety, Rapture turns from dream colony into a haven for the damned.
Why They Aren't Happening: Halo fans probably remember the details of this all to well. After taking the Alex Garland script to all of the major studios in Hollywood (delivered by Master Chief dressed couriers, nonetheless), Fox and Universal landed on a deal where they'd shoulder the weight of the film together. With Peter Jackson set to produce, and then unknown Neill Blomkamp set as the director, we looked like we had a go picture. Ditto for Bioshock, which had Gore Verbinski trying to escape the clutches of Disney with an R-rated adaptation looking to film abroad in order to secure tax breaks. This is where the heartbreak comes in: Fox pulled out of Halo, leaving Universal holding the bag. Universal didn't like the price tag they had penciled in, and decided to drop the project. Which really sucked, because Blomkamp had directed a short form live action ad campaign for Halo, which was really impressive. Not only was the budget an issue, but probably the director shift from Verbinski to Juan Carlos Fresnadillo and definitely the desire to make an R-Rated movie soured Universal on the prospect at hand. (What is it about Universal despising R-Rated entertainment, anyways?)
The Last Word?: If series creator Ben Levine is to be believed, the Bioshock movie will happen when it's ready. It's not dead, it's just resting as of last year. As for Halo, Stuart Beattie did the last rewrite, turning the film into an adaptation of The Fall of Reach. Nothing has been heard about it since 2009.
If You Really Want To See Them...: ...play the respective game series over again, as they are cinematic experiences in and of themselves. (Though you Halo fans are lucky to already have the anime film Halo: Legends and the Machinima film Forward Unto Dawn.)