Great app for kids to learn chess, as you start with a king, and slowly gain more pieces as you rescue them by solving puzzles! Initially lets kids play without knowing checkmate (instead, you capture a crown to win), and later introduces checkmate through trying to catch an injured rabbit, and eventually gets to a real game by the end (minus special rules like castling and en passant).
Very helpful app, I recommend it to any parents who want to give their kids an easy way to try out chess. My son loves it, and is now moving on to playing on a real board.