SpineChillers Mysteries Series: Birthday Cake and I Scream by Fred Katz

It's MacKenzie's twelfth birthday. He'd like a paintball party, but his mom books the party at Spookie the Clown's Hall of Pizza. Unlimited play on the video games makes it pretty cool, until Spookie shows up with some games of his own. Soon, all the kids want to win is a chance to get out!