I've only played the trial so far. In the beginning (because I never read instructions) I obviously made the mistake of not gathering enough food for my creatures. On the one hand, watching their souls floating towards heaven again and again brought in some kind of stress. And this is somehow against the concept of having no time limit. On the other hand I felt encouraged to start over and to pay some attention to the tips provided by the green flea. Even though reading instructions is against my habit, before I knew it, I was somewhere at level 14 or 15 where the brown guys come up from under earth and you have to get around them.
The game somehow managed to get under my skin. It's not as simple as it seems while playing the tutorial levels. There's a bit of pipe puzzles in it and a bit of Lemmings. Available upgrades seem to be quite interesting (f.e. storms to delete plants or the flying insects) although I did not understand yet how to earn Flowerpower which is required to activate upgrades.