Color theory is a great thing to have in your basket of knowledge.
It gives you the ability to control the kind of moods and feelings that you bring into a room.
Here's a little bit of basic info:
the color of love, warms a room, raises blood pressure,
too much can cause headache and stress
warms a room, gives room a feeling of energy (would be great for a game room),
causes hunger and restlessness (think of McDonalds, Burger King),
is a pleasing color on most people
warms a room, happy color,
can cause energy and hunger (McDonalds, Burger King),
too much can make you feel a little sick
the color of life, gives energy to a room, cool color,
too much can cause nausea
cools a room, lowers blood pressure,
can be depressing in large quantities
the true color of romance/love/royalty,
is the most pleasing color to the eye,
is the easiest color for your eye to see,
no effect when used in large quantities
And the moral of the story is...
If your room is feeling bland, dull and all around depressing,
try some greenery for starters,
then maybe change the color of something!