Let me give you a little "lecture" on what a demo is: A demo is the final product - the game itself - with very reduced content.
What you presented here is not a demo - In the description, you assumed that there are bugs, several bugs, so this is an alpha version, which precedes beta version, because it has almost none of the features intended, and, more importantly, a lot of bugs and compat issues. So, in other words, a "Very early conceptual demo" is not a demo, but an alpha.
(This may look like cheap/unimportant semantics - I assure you it is not)
So, there's the problem: alphas aren't supposed to be tested by players, because most of the time, they'll get angry over all these game breaking bugs that will come up during gameplay. That's a missile hit to their experience - that's why only Beta onwards are distributed to some of them, but this is not really a law. Being a Jam game is no excuse either.
Talking about the Jam itself: What does this have to do with cold? Let's forget for a moment that this is not the final product, and consider it a short demo: Where is "cold" in the game? There's no mention anywhere, nor to ice nor to anything thermal at all.
Remember - jams aren't kids tests where you can put super heroes over anything physical. For example: If the theme was "cold" you are not supposed to just make the entire game on a snowy environment for kicks. That snowy environment has to affect gameplay in sensible ways: Negation of visual field, taking ol' plain damage, use as cover or camouflage, you decide. And truth is, there is NOTHING COLD in this game! Nothing, at all!!! How it was accepted in that jam is a mistery - as is it getting rated as 3rd place!
So, long story short: This game is not good, nor bad. It is just unfinished. If it were a game, it would award 1 star, if any, because it is heavily broken, and also it does not fit in the jam's theme. Lack of detail is okay, I guess, not gotna pick on the dark characters. A feature is completely useless - the drone's power bar goes negative, and there is no penalty for "quick fingers". And also, this game is very far from being a metroidvania too.
The "extra" star I believe is fair because sound choice is on spot. I really don't care if it is a free library, as long as people choose the right fx, it's good. period.