From the Windows Phone Store description:
Daddy Pig is the reigning world record champion muddy puddle jumper but Peppa and George are keen to lift the trophy themselves. Play along by yourself as Daddy Pig, Peppa or George or compete against family and friends in this one touch, multi-levelled, jumping game for 1 or 2 players.
Whoever the winner, the aim of the game is to get as muddy as possible and remember - if you jump in muddy puddles you must wear your boots.
Essentially this is a really easy (as I say, aimed at 2 and 3 year olds, ideally) one-button jumping game - Peppa (or George or Daddy Pig) runs from left to right over various terrain, jumping over bushes and bouncing on trampolines... and landing in lots of muddy puzzles. It's designed so that it's hard to fail.... at all. Which is probably about right for two year old temperaments!
Grab it here in the Windows Phone Store, for a quid or so. Worth it for the peace and quiet from the little ones on a rainy day?
Just make sure you set this up as part of Kids Corner (and heeding my security caveat before doing so), so that your two year old doesn't press a Windows Phone control button by mistaake and end up phoning your boss or deleting a work email! Oh, and a rubber case on the phone probably wouldn't hurt....(!)