Thank you for trying it out! Just to give an insight on some of the things that you mentioned:
Fun & Theme:
This is our first game jam submission and first real "from the scratch" work so we only decided to create a basic platformer after feeling that our initial plan isn't going well on the first day. We had to go back to something that we're familiar with, just like what Rick and Tim advised from one of their GameDev.tv streams.
Story, Aesthetics, & Mechanics
Sadly we felt like we didn't have enough time nor experience to further flesh out the story and include it properly in the game, so we were only able to make a basic platformer with a bit of a twist.
There should be a Death and Coins counter on the upper left corner of the screen to keep track of your current "scores" for the level that you're playing on.
Regarding the hidden enemies, the game was supposed to be for a 1920x1080 resolution but I encountered issues when uploading it here so I had to downscale it to 800x600, resulting in making it harder to see some of the enemies than it already is due to the smaller area of vision. That's also why the game tutorial instructions are too big.
The hidden spikes near the cliffs and the camera not showing most of the area below were intentionally added to at least make the player more be careful when jumping and to make the game a little bit more challenging, otherwise experienced players will find the game too easy and just breeze through the game. But I guess it did make it difficult for other players, especially the players who are not used to these types of games.
And I (the developer) intentionally didn't tell the players about the dangerous Dark Water since in the tutorial there is an example of what a safe Water looks like. But I guess it won't be as obvious for the other players. I'll keep it in mind next time.
Overall, we'd like to thank you for your lengthy review. I've learned more and remembered some things that I forgot. It is a good lesson and I'll do my best to study more so I can do better next time. Thank you again for trying it out! We really appreciate it~