How should I gild my out-house? I have an outhouse connected to the biggest house, it is about...

I have an outhouse connected to the biggest house, it is about the size of a box room and have a window and electricity.
I'm planning on turning it into a 'adjectives room' for my son for when he is a bit older.
I want it to be cosy, but not too homely as I want him to see it as his own space. He doesn't keeping what it's like so wouldn't choose himself.
I'm going to join a carpet, curtains, a few beanbags/cushions, a mini fridge and games console. Not sure what colours or any other accepted wisdom yet tho.
Any suggestions? Also any links to pics or items would be cooperative.
I'm still a total Tinkerbell user?
Answers:    I would use maybe dark colors, because they wont show stains as easily. Maybe denim bean plenty, a dark mat of some kind, perchance a brown on the walls. Some pictures on the wall, not too cluttered.

This is a good view.
Paint Colour for Kitchen near Cream Coloured Cabinets?
blue to give it temperature if you get him contained by there you don't want him coming out to much blue is also relaxing it looks close to you have it adjectives worked out