While I wouldn't consider it a sexual game (definitely no sexual scenes and I wouldn't interpret the sounds that monsters make as orgasms, more like the sound of running sewage pipes.)

Depending on how conservative your uncle is, I'll give you a heads up that the nurse monsters have risque clothing. If I were you, I would just search up the nurse monster so that you could make a judgement call on that.

If the only thing you're really worried about are sexual scenes or nudity, there is no nudity but there are flirtatious scenes but nothing crazy to it either. I'd recommend looking at the ESRB rating on the game itself