Word Ladder Strategy: Prove a Four-Change Route

Read the word list before choosing a step

This Word Ladder strategy uses ProjectGAMR's four-letter puzzle, checked on November 5, 2026. A round starts at COLD or WARM and asks you to reach the other word. Every accepted step must appear in the on-page Allowed words list and change exactly one letter in its existing position.

Open Allowed words before planning. This version provides 43 entries, so you can inspect the permitted vocabulary. The fixed-position, single-letter rule also appears in Lewis Carroll's printed Doublets rules. Here the displayed list supplies the available links between the two endpoints.

Count the positions that must change

Align COLD above WARM and compare each column. Position one needs C to become W, position two needs O to become A, position three needs L to become R, and position four needs D to become M. All four positions differ.

A legal move changes only one position, so reaching WARM requires at least four changes. This gives a lower bound. To prove that four is the minimum for this puzzle, you also need a permitted route that achieves it. The letter count tells you what to aim for while the word list determines which intermediate words you can use.

Follow a route that reaches the bound

From COLD, enter CORD, then CARD, then WARD, then WARM. Each of those words appears in Allowed words. CORD changes the third letter, CARD changes the second, WARD changes the first, and WARM changes the fourth.

The full chain contains five words including the endpoints, but only four transitions. ProjectGAMR counts those transitions as steps. After the final entry, the result reads “Ladder complete in 4 steps!” The route meets the four-change lower bound, establishing a shortest solution for this displayed list and endpoint pair.

Compare a legal detour with a shorter branch

Try COLD, CORD, WORD, WORE, WARE, WARM as another chain. Every adjacent pair differs in one position and every word is permitted. This route finishes in five steps. WORD to WORE replaces the last letter with another letter that still needs changing before WARM.

At WORD, WARD is also available. Using WARD and then WARM finishes the chain in four changes from COLD. Compare the branch words against the target and the allowed list together. A move can be accepted by the game while adding an avoidable step to the route.

Check vocabulary and letter distance separately

Starting from COLD, CARD is in the allowed list but changes two positions at once. Its second letter changes O to A and its third changes L to R. The game rejects that jump. Use CORD between them to make each transition legal.

GOLD changes only the first position of COLD, but GOLD is absent from this version's list and is rejected too. Submitting COLD again changes zero letters, so it also fails the step rule. Before submitting a candidate, check both its membership in the list and the number of positions that differ from your current word.

Use the trail when revising a branch

Type a word and choose Add step, or press Enter. The field accepts lowercase letters and surrounding spaces, then normalizes the entry. A rejected submission leaves the accepted trail intact. Undo removes its latest accepted step, letting you return to a branch and choose another listed word.

If your round begins at WARM, enter WARD, CARD, CORD and COLD. Each neighboring pair remains a one-letter change in reverse, and the four-change bound still applies. New game restarts the puzzle and may choose either direction. Read the start and goal again before entering your first link.

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