Before you say anything, let’s up front agree that this is an ugly game. Ok? The theme of colored single cell bacteria with eyes being slid across a surface to go down a sink in its matching color just doesn’t work. And the animation for selecting the bacteria you want to move is clunky. And the board shifts sometimes when you really want it to stay put.
There are lots of games with this theme — Quell being the most elegant in my opinion — so why bother with this one? Simply: The levels. They are the best I have seen so far in being incrementally tricky. I played 18 levels in a sitting. With each successive round, I was literally able to see the new twist or challenge being offered. And there are several dozen levels. I’m sure there is some mathematical reasoning that could explain this in fewer words and more jargon, but I’m not going to go looking for that right now. If you like this type of game, but get frustrated when they ramp up too quickly, try this one.
Survival score: handful of levels now and then, 30-40 minutes a session.