Thanks for the feedback! I'll definitely try to do a better job with gameplay clarity and properly directing the player in the future.
Yes, the function of the spacebar is to let you "dash" to get away from the monsters. It also lets you move through walls to make it easier to get behind cover.
Each time you collect a bunny in the overworld, it follows you around. Dashing expends one of the bunnies, so your remaining dashes are measured by how many bunnies are following you.
As for getting yourself stuck in the starting area by using your last dash to get back in, I, uh... didn't think of that. It seems super obvious now that you've pointed it out. Whoops!