Sex was the most unintuitive. The prompts only mentioned camera controls and holding E to end it. Based on the above comment, I guess mouse movement was supposed to do something, but I definitely didn't notice any interactivity there.
I see that the latest update changed potion making, but at the time, the only prompts for potion making was E to brew and hold E to dump. I could drag items out to drop on the ground and managed to get some to visibly be dropped on in the cauldron, but then pressing or holding E did nothing to those ingredients dropped inside the cauldron.