The playground mode is basically a mode where you can play around freely.
- use cheats from previous games (function keys)
- you get to spawn the waves you want at a desired difficulty, when a wave ends you get to spawn a new one when you want to but you cant activate 2 waves at once
- modifiy your damage, time flow or other factors on the go (for example set your damage to 10x and enjoy it )
this game mode will award neither score, keys or any other resource or reward, it is just for practicing or having fun
in the far future, where you can create your own mission or even waves and enemies, you can use this mode to “test” if it is fun