Gateways is a game by Smudged Cat Games released for PC in 2012. Set in a 2D environment, it takes inspiration from Portal. The protagonist, a scientist, finds himself locked in a lab, and he needs to find and use the various Gateway guns scattered throughout the lab to find his way out of it.
rythin and negative_seven, however, decide to only get 2 of the normally required 4 Gateway guns, and abuse glitches to go out of bounds and help the scientist escape from the lab in record time. Please read the authors' comments for more details.
The authors also provide an encode showing the entire map and the player's position marked with a yellow dot. It can be viewed right here.
The "Minimal Obstruction" alternate encode features completely transparent graphics related to getting a power up, with the exception of the text, as it completely obstructs the view normally, and gameplay still continues while it's ongoing.