Push, or fall through the floor you broke

Twenty-five footholds. The square you leave cracks, and the next time it collapses. Push the other side into it.

A foothold falls in three states

Each time an explorer moves off a square on its own turn, that square drops one state. It is leaving that breaks it, not arriving, and the square a pushed explorer vacates is left exactly as it was.

Intact
Nobody has moved off this square yet.
Cracked
Moved off once. It still carries an explorer.
Collapsed
Moved off twice. Nothing can enter it now.

Rules

A move

Move one of your two explorers a single square up, down, left, or right. You cannot move onto a collapsed square.
Move onto a square the other side holds and that explorer is pushed one square the same way. If a third explorer stands behind it, the move is not available at all.
An explorer that was just pushed cannot immediately push the same explorer back.

Winning

Push the other side's explorer onto a collapsed square, or off the edge of the board, and it falls. That round is yours. So is a round in which the other side has no legal move left.
Two rounds win the match. Whoever lost the last round plays first in the next one.

Every ruling above is computed by a rules engine written in Rust: whether a move is available, where a push resolves to, when a round ends. The same engine picks the moves for the four AI levels — Easy, Normal, Hard and Expert — that take the second seat when you play alone. The Flutter screen only draws what it returns.

Azure and Ember

The two differ by more than colour. Azure's hood is round and Ember's is angular, so they stay apart on a screen where the colours are hard to tell. Each sprite faces the direction it just moved, jumps from foothold to foothold, and pushes with both hands. A pushed explorer lands, or falls into a collapsed square or off the edge of the board.