Firstly, making a level skip/level select and restart button a part of the user interface in the search bar was a genius idea. Secondly, the self-advertising made me chuckle, and yes it worked, Mixed Guns is now on my Steam wishlist!
Found the Flapper level extremely hard and had to skip it, but I really enjoyed the whole game. Perhaps it would be good to make it so the wall doesn't start closing in until you press a movement key to give the player time to survey the land.
Great work, good luck with your game's Steam release! Really impressive work, especially in under a day!