the instructions are in the first few levels and those levels really do not take a long time to finish. I'll write them down: "press q or p to switch", "press escape to exit", "r to reset the level", "try pushing the box against the wall"(in level 11, when the orange pushable box appears the first time) --- That are all the instructions, the rest you find out through playing: arrow keys to move, collect the yellow things, lasers get removed by pressing a pressure plate, keyhole-walls get removed by collecting the right key
While the math puzzles where a bit schoolish, I liked them far better than those where you had to guess (or probably be a native speaker to understand any hidden linguistic hints)