User blog comment:KingOfSpriters13/Video Game Shared Universe Theory/@comment-4111066-20130120220249/@comment-4111066-20130120220926

A turret from Portal appears in Shoot Many Robots, a game which also contains Gordon Freeman's suit from Half-Life

a Headcrab from Half-Life appears in Super Meat Boy which also has Steve from Minecraft

There's a Minecraft area in Borderlands 2, a game which has a Bioshock character in it

A character from Bioshock appears in PS All Stars Battle Royale, a game which is connected to Super Smash Bros Brawl via Metal Gear

Sonic is in Super Smash Bros Brawl