Drag the blocks and the gem to wherever you want them to be, you get 100 of the blocks but one gem. Click the Spacebar to start the game, the blocks make you lose when your mouse touches them, and if you click the gem you win. While you are making your level you can hover over a block and press a/d to grow/shrink.
You could show it to family/friends or you could remix it to share your mazes online. Make sure to comment if there are any bugs. There is a bug I cant fix where when you try to move a block for the first time it will create a trail following it, so move it around a little in the box before using it.