Inertia

Overview

Inertia is a route puzzle with a deliberately slippery movement rule. The ball keeps travelling after you choose a direction, stopping only when a wall blocks it or it reaches a marked stopping square. Gems are collected along the way, while mines end the current movement in an explosion. The objective is to collect every gem, not simply to reach a particular exit. You can move diagonally as well as horizontally and vertically, which creates routes that are easy to miss when reading the board as a standard maze. The engine retains an undo history, so hitting a mine does not require abandoning the entire puzzle. It records deaths while letting you reconsider the route and learn how the stopping geometry works.

How to Play

Click a position relative to the ball to choose the direction of travel. A tap above and to the right, for example, sends it diagonally northeast. Desktop players may also use the numeric keypad. The ball slides until the board stops it; tapping the destination does not guarantee that it will stop there. Collect gems while staying away from mines. If a move goes wrong, Undo restores the previous position. Restart resets the current puzzle, and New generates a fresh layout. Solve prepares a suggested route; Follow Solve hint advances it one legal move at a time.

Tips & Strategy

Plan from stopping points rather than individual squares. Before moving, trace the entire straight line to its first wall, stop marker or mine. A gem on a dangerous line may need to be approached from another angle. Work out how to leave a stopping square before using it to collect an easy gem; otherwise you may need a long detour to recover a better position. Diagonal paths can bypass narrow orthogonal bottlenecks, but they can also reach mines hidden beyond an attractive gem. Use one undo at a time to identify exactly where your route assumption failed.

About this version

Inertia uses the locally compiled inertia engine from Simon Tatham’s Portable Puzzle Collection. The original authors retain credit under the MIT license. SonoTap provides the browser adaptation and this guide.