The one rule that shapes everything
Letter Boxed gives you 12 letters arranged three per side of a square. You build words by hopping between letters, and the only hard rule is that consecutive letters must come from different sides — you can never use two letters from the same side in a row. The next word must start with the letter your last word ended on, and your goal is to use all 12 letters in as few words as possible.
Once you internalize the “different side” constraint, most of the game is pattern recognition: which letters can legally follow which.