Young men that have lived on their own a long time do have a tendency to have grossly inappropriate anger over trivial things. They've had no reason to change since they were 12.

In general I would advise talking about how that behavior scares you, that he needs to learn to know when to walk away and how to avoid frustration, and that he needs to keep in mind how other people perceive his behavior even if he doesn't feel that angry.

I would also say to you that some people, usually men, do struggle with inappropriate aggression. It's not acceptable behavior, but you also need to understand that it might a lot of self-control for them to react in the way you feel is normal. You may also have to question whether you are being a bit too sensitive about this because this is the first time you're seeing this unguarded side of someone.

I would say all that, but it seems like he's only done this stuff when he thought he was in complete privacy and for some reason you didn't tell him you were at home. It's not exactly fair to say someone needs to be considerate of your feelings when you're basically pretending you're not there.

So you need to be clear if he actually has anger issues or if he just does some crazy shit when he's alone. If it's the latter just tell him to lay off the intense video games and, y'know, say 'Hi honey I'm home' when you get in the house.