Paintball is lots of fun for everybody. Just make sure that kids are old enough to have enough dscipline to NEVER take off their facemask during the game and keep the marker (gun) pointed in a safe direction.
They are plenty powerful to inflict a good amount of damage to soft facial tissues like eyes.

FYI: Be aware that there are certain cities, like Joliet, IL that have outlawed the mereposession of all painball guns, pellet guns, and airsoft guns. Yup, it's not just about shooting one in public, or endagering someone by misusing it. They have actually taken it to the obscene level of outlawing the posession of them, even in a private residence, on private land, in a locked room, in a locked case, and without any ammo. Pretty goofy. The policewould still need to have a valid reason to search your property, but you could get nailed on your way to the paintball park.

Under these laws, I can own as many handguns, rifles, shotguns as I want, even a canon, but I'd better not have anything that spits a paintballor BBusing air pressure. Yeah, OK. That makes a boatload of sense.