Recently made a digital painting, here it is on deviantart:
Tar Monster by ~FrankieSmileShow on deviantART
A video of me drawing it:
it was fun.
Its a boss idea for Sluggy's adventures, basically. He propels himself around by shooting tar-ish stuff. The tar doesnt damage you but pushes you back. As the fight goes on, tar is building up in the bottom of the stage, and its too thick to swim in, so its as if the ground slowly grew higher or something. Its still at the idea stage though, I'm not sure about how itll work yet.