The retro vibe is PERFECT : the music, the assets, the 8-direction aiming. Really, you did an amazing job and I hope you'll be okay for your slight burn-out
Really cute ! The platforming mechanics with both the weight/size and the wind are really nice ! I got myself soft-locking in the first level (shrunk too much) and I reloaded the entire page but "R" actually reset the level (a really nice touch by the way but I'm not sure it's said in game).
Honestly, a simple but solid proof of concept. I think a progression system/deckbuilding mechanic (like the dev talked about in another answer) could easily place this game in the "Flash/In browser Games that you play for hours without realizing" category !