Click to place a block. Use numbers to change blocks: 1 - Grass 2 - Dirt 3 - Cobblestone 4 - Obsidian The semi-transparent block at the bottom left shows which block you are currently placing.
Feel free to copy this for your own games. (Either remix or See Inside, File, Save To Computer) It's recommended you play this in Turbo Mode to make the grid load faster: PC: Shift + Green Flag Other: See Inside, Edit, Turn On Turbo Mode To clear, click Green Flag.