As Drazen said, the CoG “line” is subjective, and can’t be captured in any set of rules. For example, while you generally won’t go wrong by following Mara’s “no pederasty” rule, any would-be Nabokovs out there can take heart that CoG haven’t closed the door entirely to a game that deals with those themes in an artistically meritorious manner (with the critical caveat, as long as it doesn’t get them banned from the iTunes store).
CoG definitely does not consider either consensual sex or explicit violence to be inherently offensive. So in your case, I wouldn’t worry - it sounds like you’re unlikely to trip their switches.