A fun little game! Loving the Game Boy aesthetic, brings back memories. I also enjoyed the different interesting power-ups you could find, like exploding cancer cells, that's definitely a one up from plain stat-increasing power-ups.
A bit of critique:
I think healing is bugged, as neither the "+" doors nor the "+1" doors seem to do anything.
The big dudes explosion is so quick that it seems impossible to dodge willingly.
Also, what do the stream doors do? Do they increase your movement speed?
Additionally to that, realized you could dash only after I found a power-up improving my dash :D
I think the above comments show that having a short tutorial explaining the different power ups and controls be ideal. Else, I feel that with more tweaking, it could become a very fun game. Good job!