The guy in Canabalt is Kei Kurono from Gantz
It makes sense, especially when placed into the context of the most recent arc. Think about it, Earth with tons of huge invaders in organic looking robots and the main character looks like he is wearing a suit of some sort while making massive jumps and running extremely quickly. In the manga, Kei has often worn his school uniform over his Gantz suit, a suit that amplifies human ability, allowing them to run quickly and make large leaps and bounds.
Canabalt guy is a Time Lord, specifically the Doctor.
He's wearing anachronistic clothing (check out the sweet spats), the city (which is a bleak grey — London fog, perhaps?) is being attacked by some sort of robotic menace, and he's running as fast as he can.
If we had some sort of indication that the disaster were occurring on Christmas, there'd be no question about it.
The game is in the Resistance world
Only the Chimeras can make those robots!
The humongous mechas
are synths and the missiles are prototype headcrab rockets. That design of missile was scrapped because it turned the headcrabs inside into a fine mist.
The game is set in SCP-093.
Specifically, the ruins of the city described here
. The hulking quadrupeds in the background are advanced Unclean in some sort of power armor.
He is running from a city that is being destroyed. It's likely that it is Arthur from the Hitchhiker's Guide is running from Vogon forces that are destroying his city.