A cute little platformer! I liked the music a lot, you might consider smoothing the camera a little bit and make the collision of spikes a little narrow-ish, very enjoyable platformer!
Actually there is a max enemy cap so they won't spawn until the others are dead. Glad you liked it! I will take a look at the spawn locations of enemies though you are right. Thank you!
Very good game design, really loved the idea of time limit between changes. Well polished art and sounds. Overall this is a very complete and enjoyable game, great work!