Chill. It's a bloke thing. Let him enjoy his new found space. It will evolve into a home as his social life expands or he gets a girlfriend, which ever happens first. Right now he's just enjoying the Man Cave aspect of having his own space. Buy him some beer/beverage of choice, his favourite snacks and just let him Be. He's having a blast, let him enjoy it.

Agreed. Maybe not speaking for all guys, but function over form for someone like me. After a while, and a few relationships later, my furniture is replicating faster than tribbles injected with rabbit DNA. None of it anything i find necessary, but my wife does. Also, furnishings require money, sometimes lots of it, and to be honest, it requires effort every move or whatnot that I’d deem unnecessary to put effort into maintaining or having to transfer every time i’d move, for little return than “it looks nice”, so I avoid things I wouldn’t want to have to load/unload with any difficulty unless it’s used daily. Get him a light potted (even fake) tree or something for the walls. It may look a bit better (and I don’t mean anything cutsie, unless he’s into that) when he does have someone over the first time, but it’d be something he doesn’t have to care for, maintain, and easy to move around, and likely it’ll make the place look a bit more inviting without being a burden if he moves or decides to move it around.