This is a simple engine for a game in which you build stuff. Click and hold to draw an area, but it is not solid, it is a blueprint. Hold space and draw to erase the blue blocks. Each tile takes one stone, which you have 20 of. Since this is not a full game, you can press E to give yourself stone. Hold X and draw to mark a tile to be erased. Press R to remove a mark on a tile to have it removed. Feel free to use this in your own project as long as you give credit. Warning: Do not use turbo as it causes the project to be extremely glitchy!