thank you muchly to answer your question, I mainly do it alone - I have a little help and support here and there, for instance, someone from the Stencyl forums wrote my shaders, but generally speaking I'm alone.
I think for the second game I'll need a small team to take it to the next level, but for this specific "thing" I'm doing now, a very core style game, what I'm doing seems to be working.
Are you developing the game for how long? Fulltime?
I'm asking this, because it took me (and a friend) almost 3 years to complete our game Snails, and it was much less complex (we developed it on spare time).