Use the squirrels to defend the territory and take acorns.
Defend your territory from the invasion of monsters and by the lords of the underworld.
Defend your territory from the garbage eaters with microbes.
You have a little corner of the garden, but this is invaded by boring insects, but luckily you have a range of tools to destroy these invaders.
These Humans! Are you in charge of a prison where some humans are trying to escape.
You're at war guy, defend the position and advances.
Defend your human realm, against the orcs and other animals use the towers and other weapons in your arsenal.
You're a miner who must prevent the entry of strange objects in your mine; objects that they want to take away the gold.