So: "a NPC" or "an NPC"?

[NeoCracker]

It's either

An NPC

or

A non playable character.

DUH

Except if you read NPC you're still supposed to say Non Player Character.

In all technicality your suppose to say whatever is on the paper. If it reads NPC, its said En - pee - see.

It's no different then abriviations and conjunctions. If it reads "It's" it is not pronounced "It is:", it's pronounced "it's."