This is the play room/tv room of a house that I painted about 8 years ago. I just did a very large fun check with colours we had used elsewhere in the house.
After a bit of a discussion, he let me go ahead with my idea to make his 'big boys and their toys room' into a wacky purple tartan affair, with mottled gold paint to tie in with the curtains and light fitting !
Hopefully you can see the mottled edge of the snooker tabel which is why I did the same sort of effect on the walls.
Oddly the room actually looks bigger now, even though there is a massive snooker table in the middle. The client is really happy, and his inter-changeable multi-coloured spotlights apparently look great at night. (I told you it was a big boys toy room).
I think all his memorabilia looks pretty good against the dark background and he seems delighted that the room is a one-off and basically bespoke.
I have always felt that dining-rooms, cloakrooms and obviously play-rooms are the ones you can go to town on, and the larger your home the more individual a certain room can be. This definately wouldn't work in my house, but fits well into this large country home !