This game is called Experimental Shooter, and it does exactly what it says on the tin - it experiments. Like a top down shooting Mario Galaxy, each level introduces the player to a brand new mechanics. This is a game overflowing with ideas and I love it.
Experimental Shooter leaps from twitch shooter, to puzzler, to maths question depending on the mechanic, and figuring out exactly what you have to do to progress is part of the experience.
Easily one of my favourite LunchTimeWasters.
Experimental Shooter [Armor Games]