Avoid translations whenever you can;)
( on the other hand, fuck voice over, it greatly contributed to the decline in gaming)
Do you include Fallout and Planescape: Torment in that? I think voiced over parts were an excellent ingredient in those games.
I myself can live without Voice Over, but in FO and PS:T it wasn't bad since only key npc were voiced. What I meant was that nowadays it is pretty much given that each character must be voiced else it is considered "shit" by the "new generation of gamers". This also means greatly limiting the amount of text and thus the choices in dialogs so your finances don't go too high when you have to voice so many characters.
Give them a voice for their initial "hello sentence" and select little phrases here and there, to give a sense of their character, accent and attitude, but full conversations are just painful
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