Rim (Mind Loft)

Rim is the outside sudoku on Mind Loft, a free site of daily browser games. The 9x9 grid starts empty. Around its edges, in the gutters beside some rows and columns, sets of three digits are printed. Each set tells you which three digits sit in the first three squares of that line, reading in from that edge, but not in which order. Rows, columns and 3x3 boxes still hold 1 to 9 once each.

There is no arithmetic. A printed triple works like a naked triple handed to you: those three squares hold exactly those digits, so every other square in their box loses all three. Where two triples meet in one box, they name six of its nine digits, leaving the other three for the remaining squares. The gutters left blank are part of the puzzle too. Selecting a square lights up every gutter clue that speaks about it.

Each board has one solution reachable by logic. Wrong entries are not flagged, a clean solve scores 10, and the leaderboard is a race on the clock. On your first ever play there is one free hint that fills a correct number.

A new board goes up at midnight US Eastern Time. The number of printed triples falls through the week, from 30 of the 36 gutters on Monday to 16 on Saturday, and the Sunday Edition prints thirteen. Rim belongs to Mind Loft's sudoku family with Suds, Sando (sandwich), Frame and Diag.