Virtual pet app engages kids as they care for cute alien.
Kitchen time-management sim an engaging time-killer.
Adorable sim playable without in-app buys -- with patience.
Entertaining sim experience requires patience -- or cash.
Robust building sim doesn't get bogged down in details.
Hidden instructions hamper fun in video-game company sim.
Fun, pretty frog sim could tempt kids to spend real money.
Tweens experience high school in an age-appropriate way.