I like the idea here!
But I think it might benefit from a tweak in the mechanics to allow the player to manually place units. Since they randomly spawn and the base cooldown timer for them is so long, if you get unlucky with either spawns or medal drops, you just have to wait and watch the grems slowly march toward you while waiting to spawn more deadbeats.
Could have just been me not really getting the mechanics too well, or tied into the same vein as what I was talking about above, but while being able to do something crazy like pop a sana medal into a calli medal into a polka medal on an empty row and watch a deadbeat zoom across the screen, winning didn't really feel too satisfying, to me.
Not really sure, though, would need to spend some more time playing and thinking on it to give some more solid advice, unfortunately.
But the music and art are great, so fantastic work and choice there, would be great to come back after some updates and see what's changed, if the team is willing to come back after the jam. Good work!