I'm glad you liked it!
As the tutorial says, the only lose condition is placing (locking, in tetris terms) a centrimino in a way that one or more minos (minos are each of the four blocks that form a centrimino) get placed at the outer layer (at the sides of the game screen).
Hope that helps! I'm gonna try to show some feedback on what mino made you lose in the next update.
Thanks for your comments :D