Thirdle

Thirdle stacks three words in a mini crossword: one vertical word crossed by two horizontal words, each crossing sharing its letter. The grid already opens with two letters placed in green, exactly at the two intersections, it's the starter gift announced by the rules ("You start with two correct letters"). From there, a guess only counts if the three proposed words are valid at once: the counter doesn't know the lines separately, it only knows the trio.

1. Choose your grid from the menu (Normal Daily, Bonus Daily or Unlimited) or stay on the day's puzzle, numbered in the header.
2. Spot the two letters already placed in green: they sit at the intersections, so each constrains two words.
3. Enter the three words using the virtual keyboard, with the active cell highlighted on the grid.
4. Submit with Enter: the rules require each guess to supply three valid words.
5. Read the four colors returned, then try again within the limit shown by the counter.

Because Thirdle adds a dimension single-line grids can't have: a letter can be correct but misplaced not by a square, but by an entire word. Purple turns each guess into a routing problem, figuring out where the letter goes becomes as important as identifying which letter it is. And since the two offered letters fall exactly at the crossings, the grid starts already tied: there is no free warm-up move.

Four colors, one more than in a single-line game, because you have to say which word the letter belongs to. Green: right letter, right spot, in the correct word. Orange: the letter is in this word but elsewhere. Purple: the letter exists, but in another of the three words. Black or gray: the letter doesn't serve in any of the three, or all its occurrences have already been found. Purple is the color that makes the game: it doesn't reject the letter, it redirects it.

Normal Daily

The reference grid, described by the menu as "The original daily 5-letter puzzle"; it's the one that carries the day's number.

Bonus Daily

Second daily grid, presented with words of 4, 5 and 6 letters, the lengths vary from word to word instead of being uniform.

Unlimited

Training mode without limit, described as grids drawn at random.

• Purple is an instruction to move, not a rejection: the letter is correct, it's simply placed in the wrong one of the three words. Throwing it away would waste the game's most valuable information.
• The two letters given at the start are placed at the crossings, so each serves two words at once: that's where you should build from, not from the free ends.
• Since a guess must contain three valid words, you can't test a single line in isolation. You might as well pick the two 'filler' words so they probe still-unknown letters rather than repeat a hypothesis already ruled out.