I think this game is going to remind a lot of people of the 16-bit era but to me it really feels like a PC game from the 90s. The limited, bright colors scream retro and the music reminds me of my old Sound Blaster. I'm a big fan of that era so I liked the style and presentation a lot.
There are two things that kind of turned me off from the game a bit, though. I feel it overstayed its welcome a bit; it was really fun and fresh at the beginning but by the end it was starting to feel repetitive and tedious. I think it would be better with one or two fewer levels. But that's a relatively minor complaint.
The biggest issue is the controls, or rather how inconsistent and unresponsive they can be. Double-jump only works about half the time and usually I get one shot when I fire, but sometimes none or two. It's incredibly frustrating to play because of this- a game like this needs tight controls. I died a lot because of missed shots or missed jumps. If this was fixed then the gameplay would be really solid but that soured things a lot.
I made it to the boss, gave it two tries and stopped. There was no way I was going to beat it; I have to hit it in the head, dodge acorns that drop with no discernible pattern, and hit it a ridiculous number of times to kill it. I'm not great at this sort of game; I think I would have given it a few more tries had the controls been better but I don't think I would have beat it. I think a more skilled player could have pulled it off.
Also, tab to switch magic didn't seem to do anything. Was this simply not implemented?