I'm the only spriter, music composer, sound FX designer, special effects designer, character designer, story writter, enemy designer, designer designer and pretty much everything else. Working alone allows me more freedom, to do what ever I want to do with the story or anything else.
Spriting is easy! Especially when you own a tablet. Seriously, if I can imagine it, I can draw or sprite it.
About 1/4 of the game is planned(Or the first 3 or 4 chapters) and now about 1/10th of that is done as far as overall completion goes(Of the 1/4th that is). It's not as much work as you think, especially because I barely have to code anything.