Apple iTunes has a iTunes Game App Sale: Worms 4 for $0.99 (normally $4.99).

About

The latest installment in the worldwide mega hit franchise! Play online with asynchronous multiplayer warfare. Enroll in ranked or friendly matches and show off your prowess.

New Features:

• Brand New Weapons: Wreak havoc with an assembly of brand new weapon designs including Hailey’s Comet!
• Five Gorgeous Locations: Do battle in five beautiful hand drawn regions: Middle Turf, Candiville, Wacky-Habara, Tomorrow Islands and the Fro Zone.
• 80 Single Player Missions: Test your skills against 80 single player missions. Missions are designed not only to provide the player with hours of enjoyment, but also to teach the finer points of Worms playing strategy!

Requirements

• Requires iOS 8.0 or later
• Compatible with iPhone, iPad, and iPod touch