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I thought that's just what c_scan does, except within a certain range? Anyway, how can you access a list of objects or actors in the game, to check which ones are enemies?


Quoted Impaler.
I might use eLL (entity linked lists and arrays plugin) found here for such things. I wrote it for similar purposes but I assume very few actually use it.
At one time, I clocked it, and it appeared to be faster than scan_entity. Essentially it works similarly to ent_next, and maybe scan_entity, except user-defined entity link lists can be defined. In principle, fewer items might be iterated over. A version for 6.5 is currently under revision.