The concept has legs, the music is nice, and the graphics have a nice and cohesive retro feel. Pretty good, overall! I do second what another commenter said about instructions. It took me a minute or two to figure out what I could control. 
I saw in a reply to another comment that you're new to game dev - great work for a beginner. Figuring out how to convey your controls in a FTUE isn't straightforward and lots of people at all skill levels can struggle with it.

I could have used some instructions here... Couldn't pass the first screen
Otherwise ambiance is really good!

I did not know you can throw out a hammer using shift, I only knew after ending the game(?) snipping this using windows+shift+s. The way I dispatched enemies was by dropping a crate payload on top of them.

I thought this was a good platformer game combined with just a little bit of puzzle using the bat dropping the boxes mechanic. Also I found out a way to make floating platforms by dropping two boxes in quick succession, the boxes are suspended in mid air allowing me to breeze through some levels haha.

Ideally, you could just put the controls list at the itch.io game webpage instead, so that the players could have a heads up on what to do. I was surprised to be controlling a bat at the start of the game and not knowing what it could do. *I see that at the moment of writing this, other players have already addressed these. Ah, Might as well post it since I've written it already.

Lastly, nice guitar music :)

Great game, I like the concept of playing as two characters, but I would prefer WASD for the wizard and arrow keys for the bat. You should also improve the tutorial, because for example there is a sign saying press E/B to read (and as I understand the game reading is automatically done when you stand next to the sign).

Nice game btw The music is coooooooool

Congrats! You managed to put a lot of content in the short timespan of the jam and as a solo dev!

I also think the music is great given it was made by yourself in this short amount of time. It would be much easy to just use stock music and don't tell about it, as others do.

Some constructive criticism:

Mage's weapon: If you are not planning of adding more levels where combat is more actively used, I would scrap the weapon mechanic for the wizard for this prototype. It bloats the amount of already confusing controls and it really doesnt gets applied in the level design. The couple of killable enemies in the levels are easily avoided by jumping over them.
Control layout: As they are right now they are quite confusing. It's almost like a single-keyboard-2-player game (that would work great btw). I'll simplify them as making the wizard only using the arrows+space for activating the monitors. And WASD+Q,E for the bat. (and even the bat could be simplified by removing the vertical control and adjusting the levels accordingly).
Level design: In the short timespan of a jam  it gets really hard to design levels if you also do all the other work as a solo dev. That's why I think it wouldve better to scrap unused mechanics that werent quite applied into the levels. There were 2 levels that I managed to complete only using the wizard.

I really enjoyed the short experience.

Cheers!

Unlike the other comment, I actually really like the music! Very relaxing.

The mechanics are really creative and really made me think.

I would really have liked a list of controls somewhere, I had no idea I could double jump for example.

Also, not a big deal, but if you spam 'e' the crates get stuck on the bat and don't drop.

Suggestions aside, it was very original and well put together!

Had fun playing this! cool and unique mechanic :)

The artwork is amazing! I like the interesting mechanics! The only area of improvement; perchance the music doesn't fit the game, however it is still wonderful.