The aim of the game is to fill all the target blocks (green outline), using all the number blocks (filled green)
You're the red block. Move around using , , , on your keyboard. You can push the number blocks (filled green), but cannot walk through or push any other type of block.
There are also math blocks, in the purply grey. These let you combine two number blocks by applying the operation indicated on the block. Push two number blocks onto a maths block to see it in action.
Remember, you only win when all target blocks are filled, and all number blocks are used!