First I couldn't find the level, turns out it was 'Untitled Level' by 'Unknown'. Original

Especially because I have a dozen of other untitled levels.
Also don't put 2 checkpoints at the same location, or make enemies that walk through checkpoints.
But it was fun

EDIT: I found a wall glitch, if you walk right to the room 'Extreme Precautions' (the upper part)