The concept of various & mysterious doors that lead to different places is really enticing - especially when done by the background noise. I also really liked the presence of the easter eggs in each world!
However, the movement controls were too lose, and I found myself having a really hard time getting and jumping around - which made the experience, additionally by having to restart the levels a lot of times, somewhat tiresome (especially in the last 2 levels).
But it was an interesting approach to an FPS platformer, thought!