An endgame puzzle with a long solution is usually called a study.
Here's the most famous of them all. White can't catch the h-pawn nor force through their own passed pawn. But it's White to play and draw:
[Event "?"] [Site "?"] [Date "1922.??.??"] [Round "?"] [White "W"] [Black "B"] [Result "1/2-1/2"] [Annotator "Reti"] [SetUp "1"] [FEN "7K/8/k1P5/7p/8/8/8/8 w - - 0 1"] [PlyCount "7"] [EventDate "1996.??.??"] *
Here's a really neat one with the same limited material. White to play and win, but I warn you now, distrust your first idea!
[Event "?"] [Site "?"] [Date "????.??.??"] [Round "?"] [White "No 16"] [Black "?"] [Result "*"] [Annotator "Dedrle 1921"] [SetUp "1"] [FEN "8/8/5k2/8/p7/8/1PK5/8 w - - 0 1"] [PlyCount "11"] *
Solutions:
[Event "?"] [Site "?"] [Date "1922.??.??"] [Round "?"] [White "W"] [Black "B"] [Result "1/2-1/2"] [Annotator "Reti"] [SetUp "1"] [FEN "7K/8/k1P5/7p/8/8/8/8 w - - 0 1"] [PlyCount "7"] [EventDate "1996.??.??"] {[#]} 1. Kg7 h4 2. Kf6 h3 (2... Kb6 3. Ke5 Kxc6 4. Kf4) 3. Ke6 h2 4. c7 1/2-1/2
[Event "?"] [Site "?"] [Date "????.??.??"] [Round "?"] [White "No 16"] [Black "?"] [Result "*"] [Annotator "Dedrle 1921"] [SetUp "1"] [FEN "8/8/5k2/8/p7/8/1PK5/8 w - - 0 1"] [PlyCount "11"] 1. Kb1 (1. Kc3 a3 2. b4 (2. bxa3 Ke6 $11) 2... Ke5 3. Kb3 Kd5 4. Kxa3 Kc6 5. Ka4 Kb6 6. b5 Kb7 7. Ka5 Ka7 8. b6+ Kb7 9. Kb5 Kb8 10. Kc6 Kc8 $11) 1... a3 ( 1... Ke5 2. Ka2 Kd5 3. Ka3 Kc5 4. Kxa4 Kb6 5. Kb4 $18) 2. b3 Ke5 3. Ka2 Kd5 4. Kxa3 Kc6 (4... Kc5 5. Ka4 Kb6 6. Kb4) 5. Ka4 (5. Kb4 Kb6 $11) 5... Kb6 6. Kb4 $18 *