This game is definitely among the best of the ones I've played so far! For a game made in only a few days, it feels super fleshed out, well-made and polished.
The retro aesthetics and audio are really good and gives the game a classic feel, and the gameplay is really nice too. The procedural generation is really well done and keeps the game interesting and replayable for a while. All the powerups have their place and feel good to use as does the grappling hook.
To be honest, I'm having trouble finding a criticism. I suppose there could be more enemy and obstacle variety and the procedural generation could be improved so certain coins or powerups don't spawn in places that are impossible to reach without dying but that's nothing that can't be solved by a little more development time. I also wish you could see your best score while climbing so you know how close you are to beating it.
Overall, this is an amazing entry that you clearly put a lot of time into. Good job! :)