All the backgrounds for the normal level variants are complete! New screenshots are being uploaded to replace the old ones. The Early Access period is finishing quicker than anticipated.
If you bother to read these update posts, here is a treat.
If you ever want to unlock all the levels, go to the level select screen, type in X Q X X and then press escape. Then, go back to the main menu, reenter the level select screen, and type in the code again. This will unlock all the levels for you. This was used to debug the game.