Personally, I’d go by the CoG style guide, as others have pointed out above. And taking a gander at the published games can help give a better feel for what suitable paragraph lengths look like.
Another thing to keep in mind: longer sentences and paragraphs convey a sense of passivity or calmness, while shorter ones can work well for dynamic or chaotic scenes. For example: a fight scene with long sentences and paragraphs will be clunky and boring, since a fight is more “active” than, say, shopping for groceries.
I’m rewriting a couple of paragraphs following everyone’s advice. 