if there isnt much combat in fangames is because devs keep imitating eachother all the time
I tend not to think of combat being an actual component of gameplay in 95% of the fangames available. It's just another "effect"/tool use imo. The Other Line is actually the only fangame I've seen where the combat is considered a crucial component and psiwolf has spent so much time working on their own combat system.
Personally I don't care for combat in fangames cause more often than not it's not even useful. Sure some effects/areas may hide behind a killable npc but that's forgettable. I don't play these games to kill things pretty much.