Everyone was too nice to me this time around. I set out to draw a taur, and only got three challenges. They were:

-Hard pixel edged brush only (which incidentally made fixing some mistakes a lot easier
-Specific color palette https://coolors.co/b8c480-d4e79e-92.....-501537-3c1b43
-Basic shape tools (square, circle, etc). "No lines" was said, but when I asked for clarification, "No freehand strokes" was how I went with it. Made plenty of use of the straight-line tool.

I'm up for doing a second iteration of this if I can get two additional challenges! And I'll avoid the straight-line tool as well. Half the fun of this game is finding loopholes. :D
Remember that the restrictions can be about the tools, but also the subject matter!