UI is not a problem. The problems I described above 
I will say. The fact that “more” in this case, a very small number of users… 
I want to add more.
If you want a large number of users to make large projects, then you need to show them how to properly do them. Where to start and what to do after.
Show how to create a basic game mode and basic game mechanics.
Need examples of targets for shooting. What would be in these examples showed different examples of damage.
An example of explosions with damage, not just beautiful particle effects.