The very first thing this created for me was "Titanium Dave" (pictured below) and I'm already hugely impressed.
I think it would be neat to see a game jam using these sprites for every single character. Obviously the scenery etc. would still have to be made with something else, but maybe there's a similar tool out there for that? I know you say this is mostly just a starting point but I think it would be a fun limitation to work with.