The concept seems interesting though some of the design decisions are a bit weird...  it was a fun playthrough though and it'd be interesting to see where it could go with some more work on it.  

A bit of finer feedback on what I mean:

• A few slight UI changes would help, specifically, and this may be more personal, but the fact that the "cards" were shown at the top of the screen was a bit weird.  Though it does somewhat work personally when I think of a "card" game I think of it being at the bottom.  
• As for the main loop, it seemed interesting. Though honestly when I heard a card game I was thinking it might be a more complex use of the actual cards rather than just trading away 3 colors of cards.  It's still interesting but I feel like there's definitely a lot of room to tweak it and add some extra stuff.  Though obviously, it's a jam game so there's only so much you can do.  
• The color skew seemed to be a bit weird, mostly in the fact that even though you start with the same number of each color they seemed to show up with blue as the most common and purple as the least common.  Which lead to a lot of the points being very rng heavy.  Maybe leaning into that by tweaking the starting number of each card could be interesting?  That could add some variation to gameplay.
• It was a bit weird that the entire game is on a timer.. cause it seemed more like a puzzle game when I started it, but then it's forced on a short timer.  Plus considering the fact that just clicking a "trader" takes the cards instantly, I feel like maybe making it a bit more interactive could make it more engaging and a little easier?  Something like dragging the cards from the bottom to the "trader" you're interacting with.  That way if you're part way through you can realize there's someone else to trade with etc.  Adds a bit of strategy.

Overall though it's a nice little time waster, one small suggestion someone I know did say though is that maybe completing a trade should increase the timer.  That could lead to a high score -esque playstyle.

It's really interesting, but need to be polished

I like that it can be played in two ways - the highest score and the lowest

And please add text to your menu, cause I didn't understand that the second button is a tutorial :)