Great idea, and well executed. I promised I'll give some constructive criticism, so I have a few positives and only really a couple of negatives.

For starters, game feedback for the player in this game is some of the best I have seen so far in this game jam. People seriously underappreciate how far adding some sound effects or death animations can take a game in terms of quality. Literally the only game feedback that the game is yet to provide is some sort of indication of what potion the player is currently using in the shooter game, and how much time that potion has left before it runs out. If you did implement this, it's really difficult to tell, so I'd suggest making that a bit more obvious if this is the case.

Secondly, the amount of polish that went into this game is really good. I can easily tell what's good and what's bad just by looking at them because you've done a really good job of indicating this to the player through visuals and effects like particles and lighting. This might sound like a dumb thing, but having a game where the player already knows what to do just by looking at the screen is a huge accomplishment. No tutorial necessary here.

My biggest issue with this game is that it feels like I'm playing two separate games. Each game mode should like to each other to feel more like one game. Even just a proper cutscene to blend between the two game modes will do wonders to improve this. I personally think you should take it a bit further, and have the two game modes interact with each other. How you do in one should affect your conditions in the other. Maybe the shooting game mode will spawn enemy bodies in the platformer that the player can move around to help them reach higher platforms or keys. Maybe the keys the player collects in the platformer can unlock more areas in the shooting game mode to reveal more weapons and more enemies. There's a world of unique opportunities that are being missed here, and I seriously think you should look into these opportunities if you wish to develop the game further.

Another thing that could be improved is the movement in the platformer. For starters, double jump. Developers don't like adding double jump, but quite simply put it's always a really good feature to add to any platformer. Also, player deceleration should be much faster than the player's acceleration. I don't enjoy having to reset because the character decided to walk an extra mile after I had already let go of the key. The character should really only be moving another half a step at most once the player has let go of the move key. And finally, make the player a bit faster. People like snappy controls, and increasing the speed of the player ever so slightly can go a long way. It never feels like it, but trust me on this one.

My only other issue is a much smaller one. When in the platformer, don't keep the player directly in the center. I couldn't care less what I've run past when I'm in that platformer. I want to be able to see what's ahead of me, and I want to be able to see a lot of what's ahead of me. Or, maybe the camera can be programmed to have certain anchors, so that as a player walks into an area, the camera pans out to reveal everything about this area to a reasonable extent.

I hope my feedback was helpful! If you have any questions or concerns, don't be afraid to bring them up :)

Absolutely Wow. I was a little bored at first and died alot collecting the keys but then the timer ended and I found myself in a top down shooter Doom style game and absolutely loved it. 

Likes

+2 different game modes

+You can take it slow in the platformer and go crazy in the shooter

+Potions effects were cool and helpful

+Music in amazing and changes every time

+Variety of Demons spawning

+Screen transition is cool

+Boss fight was awesome

Improvements

-Potions spawns outside of walkable terrain when close to the walls

-Found the platformer harder  (Died10 times ) than the Top down shooter (Died once)

-Found a bug when you died in the platformer just as your about to get into the shooter, your character is stuck at one place, along with the timer.

Awesome idea!!! Love it! Really fun game. 

Would be interesting some kind of repercussion between the platform and the top-down, like sharing health, or something. On the Top-Down I always ended surrounded by monsters and then came back to the platform as if nothing had happened. Could be really interesting some kind of connection between them.

Very entertaining game. Seriously.

Great job! Congratulations!