Inertia
Why do I lose after collecting the last gem in Inertia?
Gems do not stop the ball. It keeps sliding until a wall or stop arrests it. Hitting a mine later in the same move still loses, even after the last gem has been collected.
Worked example
Before moving through the last gem, trace the whole slide to its endpoint. A safe gem square is not necessarily a safe move.
What to check on your board
Apply the rule above to your current board, then verify the remaining puzzle constraints. The example explains a local deduction; it is not a solution to every randomly generated board.
Checking your next move
Trace the route beyond every gem until the ball reaches its actual stopping square. Check that full route for mines before making the move. When the last gem is on the path, keep tracing: collection does not cancel the remaining part of the slide.
Using this reference
For Inertia, read the rule and the worked example together before opening the game. Separate what the rule explicitly requires from what only seems likely on the current board. A useful next move is one you can explain from the visible constraints, not merely a pattern that looks familiar.
If you get stuck, isolate a smaller part of the position and list what is still possible there. After a move, check the affected rows, regions or connections again. The reference explains the documented rules; progress, controls and save behavior belong to the linked game.
Read the developer’s manual ↗ · Open the developer’s browser version ↗
Manual inspected: · Simon Tatham & contributors · MIT