This game is really fun and looks great. Shifting whole rows is a lot more interesting than the games where you only swap one object and the combo meter is really cool. I think the biggest issue right now is gameplay polish and balancing. Here are some issues I encountered:
-sometimes germs don't fall and stay in the air until you move them again
-sometimes germs can overlap in a cell (I understand this might be hard to find a satisfying solution for)
-clicking next level on the fifth level softlocks the game on a black screen
-I think the timings between waves is kind of messed up so that you sometimes have long stretches of nothing happening and then two waves appear at the same time (happened to me a lot in level five), the long pauses are especially annoying since you will lose your combo and building that back up can be really hard
-I think related to that I got stuck in endless at 999702 remaining with nothing falling down anymore
-while the combo is really cool it's also super punishing when you lose it, I think it can stay like that, but if you want to make it a little less punishing you could make it so that instead of losing the whole combo it goes down gradually like it is building up so after combo level two runs out you have a new timer of combo level one until it goes back down to zero
-maybe there should be a general beck button so you can exit level select without having to enter a level
Again, really fun game, I love the idea and the execution is already pretty good.