If you make a mistake, and don't save enough Darwinians on any of the levels which require a certain number, there's no fixing it. You have to do the whole ♥♥♥♥♥♥♥ level over again from the beginning.

I went into this knowing that full well, and still managed to ♥♥♥♥ up. One of the levels is called Escort, where you have to escort a bunch of Darwinians to the other side of the map. Except that's not actually right, because if you just escort the Darwinians to the other side of the map you fail and have to do the whole ♥♥♥♥♥♥♥ thing over again. Because there aren't actually 250 of them, which is how many you need.

I failed to notice that there was an incubator in the level, so I thought I wouldn't need to collect any of the souls from the killed viruses, and didn't bother. Oops. Got to the very ♥♥♥♥♥♥♥ end and realized there was no completing it.

Forcing the player to do an entire level over again from the beginning, after getting all the way to the end, is not something many games do. But this one does. And that is some annoying ♥♥♥♥♥♥♥ ♥♥♥♥.