Sure, if the 12-year-old is mature enough to play games rated "T" for teens.
They can play Runescape.
Ten year olds can play moviestarplanet and girlsgogames
Not if it is playful with other 4 year old, or people mature enough to know how to play with a 4 year old.
No. That is, it's not an inalienable right of a 10 year old to play war games if his or her parents don't want him to.
maybe... video games?
Games have a Rating for a reason. Your question tells me you are not mature enough to play the game, if you were old enough you wouldn't need to ask this question at all.
depends what games your playing
No, his face will not be mature enough.
yes
yes
play video games..