I played it for quite a long time. I think the gameplay lacks of accuracy, the character is often sliding a little bit, the keys are not well chosen imho, etc. But it's ok, it was good enough to enjoy the game. The main problem is just that I was stuck because of a bug: one of the grass items to make me jump had disapeared and I couldn't jump over a magma area. After that I was respawned infinitely in a hole. It's a shame, I wanted to know what the key could open!
The graphics were very nice, the intro was excellent. The music was good too but maybe too repetitive, it would have been nice to change it after a while when the challenge increases. There are a lot of good ideas in this game: the plants objects, the fountains to regain health, etc. The main biggest issue finally is the lack of explanation on the gameplay: I had to die a few times until I found that Space was to jump and X to interact with the surroundings. After the intro you're suddenly fighting a golem without any info about your character abilities! ahah
Long things short: good! Polish it a little bit and it will be great :)