The game has been mostly completed, but plans changed so I need to add a 7th level for the final boss' 2nd phase. Sorry for not posting before, I'm busy with school. Attached is a template spritesheet that you can download for mods when played on Flowlab.
I will fix the download now. The Leaderboard is a feature that only works on the Flowlab.io website, so I will disable it unless you click on it so that it doesn't pop on its own anymore.