"Please take the gifts in these chests, for they will aid you on your quest." This sentence is comprised of two independent clauses (each could stand alone as a complete sentence) which are joined by the conjunction "for", and should technically have a comma.
"Also, speak with the guards, for their knowledge can help you." In this sentence, "Also" is an introductory clause and should technically be offset with a comma. "Speak with the guards" and "their knowledge can help you" are, again, two independent clauses that are joined together with the conjunction "for".
These are the kind of comma errors that are unlikely to stand out to anyone except professional writers/editors/English teachers. I'm a writer myself, but I personally wouldn't bat an eye at this kind of thing in a video game, as it's fairly frequent.
Those are the kinds of missing commas I was talking about. Guess I'm a professional English teacher if they immediately stood out to me that much. Sorry to bother you, then.