This game is called First-Person Tetris, which perhaps isn't quite the best description of what's going on here, but still... you must play it. Especially the 'Existential Crisis' mode, which may just make your synapses collapse and beg for mercy.
Essentially what is going on is the screen rotates as you rotate each Tetris piece. When you crank it into Existential Mode however, your perspective becomes even more claustrophobic and things get a little more complex!
Argh... my brain!