Deep Sea Trijong

The tiles in Deep Sea Trijong are triangles rather than rectangles, and that single change rewrites how a board is read. A triangle has three sides, so a piece counts as open when nothing sits on top of it and at least one of those three edges is clear, which makes the blocked-or-free judgement slower than on a standard layout.

The setting is an underwater one, with reef colours and sea creatures on the faces, and the run stretches across forty-one stages that tighten as they go. Each stage carries a timer: clear the arrangement before it empties, or start the stage again. The same free-tile rule governs the Cartoon pile.

Matching works piece by piece. Select two identical open triangles and they leave the board, exposing whatever they were covering. When the visible matches run out, a shuffle redeals the remaining pieces and a hint will point at a legal pair, but both are limited resources worth saving for the late stages. The Tiles Matching pile lays the same tiles out in another silhouette.

Built in HTML5, the game scales from a desktop monitor down to a tablet, and full screen is the sensible setting because the triangular faces are small and several of the reef motifs look alike at a glance. Freeing the lower rows early matters in China Tower as well.

1. Pick out two identical triangles that are uncovered and have at least one of their three edges free.
2. Remove the pair, then reassess, because every triangle you lift changes which neighbours are now open.
3. Work down through the stacked pieces rather than around the fringe of the arrangement.
4. Empty the stage before the timer runs out to reach the next of the forty-one levels.

• Check all three edges — a Deep Sea Trijong piece can look buried and still be legal, because a triangle needs only one free side.
• Clear the peak first — the top pieces unlock the most, and the reef motifs underneath repeat more than they appear to.
• Shuffle before you stall — reshuffling with seconds left rarely leaves time to use the new pairs.
• Save hints for the later stages — the early arrangements are readable without them.
• Play in full screen — small triangles and similar sea-creature faces are a bad combination in a shrunken window.