I LOVED the voice of main character being hurt, it made me die more times than I should ;) Very nice visuals as well. There was some stutter like 2-3 screens right of the beginning, probably due to lighting and maybe some shaders compilation? It happened both times I went there though. It could be a bit faster, but that is a personal preference, it was still pretty hard to beat (and I didn't beat the whole game), if you want to develop this further you can experiment maybe with Arnio gaining momentum when he starts moving faster and faster? Something like in Super Mario (which I see in other comments you pointed as your inspiration) ;) It took me an embarrassingly long moment to realize I can use double jump to exit the "pit" between two columns near the start of the level once I fell there. Nice platformer overall!