Gazillion's kid-friendly Super Hero Squad Online MMO.
The Super Hero Squad TCG features a 300-card base set chock-full of the usual Marvel suspects. Alongside the Spider-Man, Wolverine, and Captain America cards are special loot inserts with reward codes that unlock bonus items and exclusive playable characters in SHSO. Look for booster packs at your favorite gaming retailer on April 24th.
[Source: Marvel press release]