FREE - In Google Play
FREE - in Win Phone Store
Alright, I took it to Stockfish to see what's wrong with 1.e5+ fxe5+ 2.Ke4. Play continues 2...bxa4 3. bxa4 c5 4.f6 c4 5.f7 Ke7 6.Ke3 Kxf7 and now it is black who has multiple passed pawns and white can't stop them all. Recognizing that white must push the b pawn now or never, or else black will have a passed c pawn, is the key to this puzzle.
Wow! That was a lot of fun, Bub!!!