Playtesting turned out possible (just really hard). Now it's again a WIP, so I removed the button to playtest. But you can play around on this editor, build your own layouts, save them as files and load them up later and plan your future GD layouts here to build soon for the actual GD game.
Please only place 150 blocks per page, the rest won't show up otherwise. If you want to load a piece of data, remove your level first, so it can be uploaded.