Enclose the Horse: Knight Geometry and Cornering Tactics

Enclose the Horse turns a chess knight loose on a grid and asks you to trap it, one wall at a time. Each turn you place a single wall on an empty cell; then the knight moves. You win the instant the knight has nowhere left to go. It sounds simple, but the knight isn’t moving randomly — it always picks whichever open move keeps the most future options available, with a slight preference for the edges. Beating it consistently takes an understanding of knight geometry, not just wall-spamming. Play along at the Enclose the Horse board.

Why the knight is hard to pin down

A knight in the center of an open board has up to eight possible moves. Every wall you place removes at most one of those, and the knight moves after your wall — so a single wall placed near it usually just nudges it toward one of its seven remaining options rather than trapping it. Worse, the knight actively favors moves that preserve mobility, so it tends to drift toward open space rather than into corners on its own.

This means early walls placed directly adjacent to the knight are usually wasted: you spend a turn, the knight loses one option out of many, and it simply takes a different one. The knight only becomes vulnerable once its mobility is already low, which is a state you have to engineer over several turns, not force in one.

Corners and edges have fewer exits

The core geometric fact that makes this game winnable: a knight near the center of the board can reach up to eight cells, a knight one row or column in from the edge can reach up to six, a knight on the actual edge can reach at most four, and a knight in a corner can reach only two. Fewer legal destinations means fewer walls are needed to close them all off. That’s why the strategy isn’t “wall off the knight where it stands” — it’s “walls that steer the knight toward a low-mobility region, then finish it off once it’s there.”

Because the knight’s own move selection already leans toward edges when it has to choose between similar-mobility options, walls that block its access back toward the center are often more valuable than walls that block its escape outward. You’re not fighting the knight’s edge preference — you’re exploiting it, then closing the trap once it commits.

Reading the possible-move markers

The board highlights the knight’s current legal moves before you place your wall. Use this actively: placing a wall on one of those highlighted cells guarantees you remove exactly one option this turn, rather than a wall placed elsewhere that might not affect the knight’s mobility at all this turn (though it may still matter later, once the knight has moved into range of it).

A useful mental model is to count the knight’s current option count each turn. If it’s sitting at five or six options, most single walls barely dent its mobility. Once it’s down to two or three — usually because it’s been pushed into a corner or against two intersecting walls — a single well-placed wall can end the game outright.

Wall economy: don’t overspend early

Because every wall placement also gives the knight a free move, wasting walls early effectively gives the knight extra turns to reposition into open territory. The efficient approach is patient: spend the first several turns placing walls that gradually shrink the knight’s accessible region — favoring cells between the knight and the board’s open center — rather than walls immediately next to its current square.

Watch for natural chokepoints: cells that sit on multiple of the knight’s potential future paths, not just its current one. A wall there pays off across several turns instead of one, since it keeps limiting options no matter which of several nearby squares the knight ends up on next.

Finishing the trap

Once the knight’s mobility count drops to two or fewer, look at where those remaining moves lead. If both remaining destinations are themselves low-mobility squares (say, both corners or edge cells), you’re close — a wall on one of the two remaining exits, followed by a wall on whatever’s left after the knight’s forced next move, usually closes it out within a turn or two.

The pattern to internalize: don’t chase the knight’s current position, corner its future options. Every wall should be chosen with the next two or three knight moves in mind, not just the one immediately available.

Why chasing directly rarely works

New players often try to place walls in a tight ring immediately around the knight’s current square, hoping to box it in on the spot. This almost never works against an opponent that actively maximizes its own mobility, because a ring that isn’t yet complete just tells the knight exactly which gap to escape through — you’re giving away information about your plan a turn before you can execute it, and the knight’s move-selection logic will reliably take the escape route you left open.

A better mental model is to think in terms of territory rather than position. Instead of asking “how do I block the knight right now,” ask “which region of the board do I want to force the knight into over the next several turns, and which walls make that region smaller each turn without tipping my hand too early.” Walls placed on the boundary of a region, rather than directly adjacent to the knight, tend to be harder for the knight to route around, because they constrain multiple future paths at once rather than just the current one.

Difficulty and board size

Larger boards and higher initial wall counts change the calculus somewhat. On a bigger board, the knight starts with more open territory to retreat into, so early walls need to focus even more on limiting that retreat territory rather than reacting to the knight’s immediate position — the region-shrinking approach matters more, not less, as the board grows. Pre-placed random walls at the start of a round can occasionally work in your favor by accident, narrowing the knight’s natural escape routes before you’ve spent a single turn, so it’s worth taking a moment at the start of each round to notice whether any starting walls already constrain part of the board usefully.

Enclose the Horse is part of the Daily Puzzle rotation alongside six other games, if you’d like to make trapping the knight a regular habit.