- Single scale_target (and changed hierarchy) so that everything stays in the same relative position while growing.
- Variable rate spawning.
- Level doesn't add Geometry since now we have an instancing plan.
- Auto queue-free if we fall too far. Just in case.
- Monsters now take damage and flash and maybe shrink into oblivion.
- Gems which can be picked up.
Needs more thought and smoothing over.