This game has a lot of effort put into it from all departments that worked on it. The music and sound effects were good, the art was very unique, and I didn't run into any noticable bugs or gameplay issues (apart from the slimes glitching a little when they were spawnning in large numbers, but it didn't affect gameplay).
That being said, the one issue that I personally have is that the game becomes very repetitive and there is nothing that really forces you to be careful. Sure, the enemies increase as well as the timer, but from what I've seen the enemies don't get stronger or get any additional variety. Seeing as how slimes appear to have a sort of wind-up attack, have you considered adding an enemy with a shield? The player might need to hit, dash away (which could force them to end up in a dangerous spot with other enemies) and they go back and kill it.
Or how about an enemy with an AOE damaging aura? They can limit free movement even more. Once I got enough upgrades I pretty much just bulldozed my way through since the slimes take a while to attack, and their numbers doesn't make that much of a difference.
However, the Jam itself was only 3 days and for it's purpose, the game has delivered more then needed with all elements working together good.
If you do plan on improving the game, considering adding some more rougelike elements that make it difficult or require strategy, like a stamina bar on dashes, more enemies, maybe even random debuffs along with the buffs you gain at the end of each stage, and so on.
Great job :)