Had a quick play on my 'totally legit not chinese bootleg' handheld, ran flawlessly. A little more difficult than expected - I think on some screens the spikes blend in with the regular collision a bit, but the game is 100% my kind of thing :)
I was wondering how exactly you were handling screen to screen navigation, and what you have is great (once I realised d-pad inputs could adjust the direction to go in).
Though I did end up trying to evade a HP refill after thinking it was another power-down coming straight for me :P