Neil’s crackers

   [FEN "3k4/3p4/3p4/p2P2p1/P2P2P1/3P4/3K4/8 w - - 0 0"]   [White "White to play and win"]   1. Kd1 $3 ({White gets nowhere with, e.g.} 1.   Kc3 Kc7 2. Kc4 Kb6 {and White cannot make progress.  The only way to do it is   to "pull the cracker".}) 1... Kc7 (1... Ke7 2. Kc2 Kd8 3. Kd2 {comes to the   same thing}) 2. Ke2 Kd8 3. Kd2 $3 Ke7 (3... Kc7 4. Ke3 Kd8 5. Ke4 Ke7 6. Kf5 {   and wins, rather more straightforwardly than in the line where White is left   with a rook's-pawn}) 4. Kc3 Kd8 5. Kc4 Kc7 6. Kb5 Kb7 7. Kxa5 {And now White   will eventually win, by giving up the a-pawn for both Black d-pawns, e.g.} Ka7   8. Kb5 Kb7 9. a5 Ka7 10. a6 Kb8 11. Kb6 Ka8 12. Kc7   

  [FEN "2n3r1/4b3/1p1R2p1/qPrb4/P2kp1KN/1PpBp3/2P5/3R4 w - - 0 1"]   [White "White to play and draw"]   1. Nf3+ $1 exf3 2. Bf5+ Ke5 3. R1xd5+ $1 Rxd5 4. Re6+   Kd4 5. Re4+ Kc5 6. Rc4+ Kd6 7. Rc6+ {and so ad infinitum}