If Tony Hawk didn't land the 900, apparently the consequences would be so dire that the entire world would become a psychedelic skating wonderland according to Perfect Stride. Also the laws of physics would break to the point where you can now skate on the ceiling.
The developers call Perfect Stride a "first-person maximalist skater for PC & OSX," and they say it's based on "old school FPS movement exploits" like Quake jumping, Tribes skiing, and Counter-Strike surfing. And according to the (utterly fantastic) website, the controls are "hella hard" but that's intentional.
The game is only available to people who funded the LA Game Space on Kickstarter, although there are plans to allow people to donate to that project (and thus receive a copy of Perfect Stride) in the near future according to Rock Paper, Shotgun.