Object oriented Python noodling.
- temporary power-ups
- make snake not die when colliding with walls (this is the default right now, needs to change when feature complete)
- speed up snake
- slow down snake
- background flashes distractingly
- snake starts out not as white cells but as three digits of π (its head is 3, with 14 dangling behind it), snake food is always the next-in-line number of π, and when the snake eats the food, the digit shows up at the end
- pause key combination