Only Knights

You start on a1 (bottom-left), your opponent starts on h8 (top-right). The first move is chosen at random each match — sometimes you go first, sometimes your opponent does. When it's your turn, tap any pulsing dot to move your knight there — the pulsing dots mark every legal destination from your current square. Every square you leave turns permanently dead (the × mark). You can never re-enter a dead square, and neither can your opponent.

In Capture mode, your opponent's square is also a legal destination — landing on it captures their knight and wins the match instantly. Capture-legal squares glow red. In Classic mode you win only by leaving your opponent with no legal move of their own.

Streak mode runs matches back-to-back. Your run continues as long as you keep winning. The first match you lose ends the run, and your longest streak becomes your score. Single plays one match with no leaderboard impact. Speed is Streak with a 10-second per-move clock — miss the clock and you lose that match.

The Hint button (or press H) highlights a recommended move for your knight. Hints are free to use — they don't end your streak or disqualify you from the leaderboard — but your hint count lands in the summary and share grid, and ties on the local leaderboard break in favor of fewer hints. Concede match takes the current match as a loss without playing it out.

Only Knights is an abstract strategy game — no randomness, no hidden information, no dice. Both players see the entire board, both have the same piece, and the only lever either of you has is which square to move to next. Games like this reward a particular kind of thinking: reading the position, planning a few moves ahead, and refusing to fall in love with any one move until you've checked the next one. The answers below cover the skills that actually win these games.

How does the knight move?

In an L-shape: two squares in one orthogonal direction (up, down, left, or right), then one square perpendicular to that. That's the only move the knight has, and it's why knights are the most mobile piece in the opening and the most awkward in the endgame — their moves don't line up with the intuitions you build from other pieces.

From any square well away from the edge, a knight has eight legal destinations — four L-shapes, mirrored left/right. From the corner, it has two. From an edge square (but not a corner), it has three or four. This mobility-by-location asymmetry is the single most important fact in the game.

What is a knight-isolation game?

An isolation game is an abstract-strategy format where each player controls a single piece, and the square a piece leaves is marked permanently unusable. Play continues until one player has no legal move — that player loses. Isolation games are a tiny family (fewer than a dozen well-known ones) but they're a great teaching vehicle because the rules fit on a sticky note and the strategy is deep.

A knight-isolation game is the variant where the piece involved is a chess knight. The knight's awkward L-move combined with the shrinking board makes it much richer than a king- or bishop-based isolation game. The knight can't retreat along its own path — whatever squares you used to get to your current position are gone — so every move is a commitment.

Classic vs Capture — what changes?

In Classic, landing on the opponent's square is illegal. You win only by leaving them no legal move. The game tends to last longer, play more positionally, and turn on subtle space-management decisions. Good Classic play looks patient — you're squeezing the opponent's mobility down one move at a time.

In Capture, landing on the opponent's square is legal and wins instantly. The game plays faster, more tactically, and often ends in fewer moves. The tension is mutual — either knight could be captured at any moment if the opponent gets a free shot — so you're always watching two things: what the opponent can do to you this turn, and what they'll be able to do next turn.

Practical difference: in Capture, you often have to reject your best positional move because it would leave your knight capturable. In Classic, no move is outright losing-on-the-next-turn — the game is pure slow pressure. Most players find Capture more fun the first few games because the stakes feel higher; Classic grows on you as you start seeing the longer-range plans.

Why are corners so dangerous?

A knight in the corner of an empty board has exactly two legal moves. From a1 those are b3 and c2. That's it. The corner is the lowest-mobility square on the entire board.

In an isolation game, any position where your knight has only two legal moves is one move away from a position where it has one (the opponent just has to block one of the two). And one legal move is one move away from zero, which is losing. So corners — and to a lesser extent, other low-mobility edge squares — are traps.

Walkthrough — the corner squeeze:

1. Your knight is on a1. Legal moves: b3, c2. (Mobility: 2.)
2. Opponent plays to b3 (blocks it). Your only legal move is now c2. (Mobility: 1.)
3. You move to c2. Your a1 square is now dead. Opponent plays to block one of c2's legal moves.
4. The noose tightens a move at a time. Unless you can force the opponent into a worse position right now, this ends with you stuck.

Shortcut: keep your knight where it has at least three legal moves. When mobility drops to two, you're already in trouble — find a move that restores mobility, or find a move that drops the opponent's mobility even faster.

How do I read a knight-isolation position?

Count two numbers: my mobility (legal moves for my knight right now) and their mobility (legal moves for theirs). Then compare.

• Ahead on both numbers, opponent is in the corner or near it: you're winning. Close down their escape routes without compromising your own position.
• Similar mobility, middle of the board: it's an open position. Play the move that drops their mobility more than yours.
• Behind on mobility, near the edge: you need to complicate. Look for moves that threaten two of their destinations at once, or that force them into your half of the board where you can create more dead squares around them.

The trap to avoid: hoarding your own mobility. A move that keeps your options open is great if it also hurts the opponent; if it's just "safe," they'll use the turn to squeeze you anyway. Isolation games reward moves that do two jobs — improve you AND worsen them — over moves that only do one.

What does tempo mean?

Tempo is a word borrowed from chess. It literally means "a turn" — one player's move. You have a tempo advantage when every move available to your opponent makes their position worse, and at least one move available to you makes yours better. In that scenario, each exchange of moves widens the gap.

The classic tempo-winning move in a knight-isolation game is one that threatens two opponent destinations at once. They can only defend one, so the other goes to you next turn. You didn't gain material (there is no material), but you gained a turn of initiative — a tempo.

Why it matters in practice: end-of-game isolation positions often come down to a single-tempo race. Both players' knights are cornered, both players have one or two legal moves, and whoever runs out first loses. The tempo swings you built five moves earlier are what decide that race.

How do I plan two moves ahead?

The simplest reliable technique:

1. Pick your two or three candidate moves from the current position. Don't try to evaluate all eight — just the ones that pass a first-glance sniff test.
2. For each candidate, mentally make that move, then mentally make the opponent's best reply. Their best reply is usually the move that most reduces your mobility in the new position.
3. Count your remaining mobility after their reply. That's your depth-2 score for the candidate.
4. Pick the candidate with the highest depth-2 score. If two are tied, pick the one that also drops the opponent's mobility the most.

This is exactly what a chess engine does at depth 3 — your move, their best reply, your evaluation. Done by hand it's slow and fallible, but it's dramatically better than picking the first move that looks good.

Don't plan deeper than two moves by default. Three moves ahead (mine-theirs-mine) is the upper limit for most humans without a notebook. Four moves ahead is professional-chess territory and requires specific training. Most positions in Only Knights can be played well at depth 2; the few that can't are usually late-game squeezes where you can count to the end of the game directly.

Do strategy games train decision-making?

A little. Research on expert chess and go players consistently finds narrow transfer: these players are better at tasks that closely resemble the game they've trained on (pattern recognition in similar layouts, multi-step planning on gridded problems) and no better at tasks that don't. Playing a thousand games of chess does not reliably make you better at chemistry, writing, or taxes.

What abstract strategy games do reliably build:

• The "what happens if I do this" reflex. Players who've drilled turn-based games for a while tend to imagine consequences before acting, even outside the game. That habit is small but genuinely transferrable.
• Comfort sitting with an unsolved position. Most people make snap decisions to escape ambiguity; strategy games reward pausing in ambiguity until the right move reveals itself. The ability to not-decide for another ten seconds is itself a skill.
• Resistance to tilting. Playing through a losing position without giving up early is a learned skill. Isolation games that drag on after you've lost tempo are good practice for it.

Don't expect Only Knights to fix bad life decisions, but don't dismiss it either. The thinking style is real; the transfer is narrow but not zero.

Who designed the original game?

The knight-isolation pattern was popularized by German game designer Alex Randolph (1922–2004) in his 1970s game Pferdeäppel — which translates roughly to "horse apples," a pun on the droppings the knights leave behind as they move. Randolph was one of the most prolific abstract-strategy designers of the 20th century, with over 125 published games including Twixt (1962), Inkognito (1988), and Ricochet Robot (1999). Many of his designs are still played competitively today.

Only Knights is an independent implementation of the knight-isolation mechanic. The rules of a game are not copyrightable under US or EU copyright law — what's protected is the specific artwork, text, and branding of a given published game. This page attributes the pattern to Randolph because he deserves credit; it isn't a licensed digital port of any specific published product.

Is this Pferdeäppel / Knight Chase / Plop!?

Yes — those are all names for the same game. Only Knights is a free browser implementation of the two-knight isolation game Alex Randolph designed in the 1970s. It's known as Pferdeäppel in Germany (literally "horse apples," a cheeky reference to the dead-square marks knights leave behind), as Knight Chase in English- language board-game guides, and was re-released in Italy as Plop! The rules are identical across all versions: two knights, one shrinking 8×8 board, last one with a legal move wins. Only Knights isn't a licensed port — it's an independent implementation of a public-domain game mechanic.

Related drills on Practice

Memory Sprint is the closest cousin to the "plan two moves ahead" skill — holding a sequence in your head while reasoning about it. Quick Math trains the same working-memory loop with arithmetic instead of positions. Making Change, Percentages, and Fractions are the mental-math side of the site. Only Knights is the lone strategy drill in v1; if you enjoy it, the others closest in flavor are the timed recall drills (Memory Sprint, Quick Math) where the pressure is thinking, not reflex. Tape Measure is the hands-on skill drill on the opposite end of the spectrum. Change a Tire is the site's first Life Sim — a procedural recall drill on a 12-step real-world skill, with Build, Spot-the-mistake, and Speedrun modes.

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• Wooden chess board & pieces (tournament size) Playing Only Knights on a real board, with real pieces, makes the mobility-and-tempo instincts stick faster than any screen version can. A plain weighted-plastic-piece tournament set does the job — no need for a fancy staunton collector board.
• Twixt — Alex Randolph Randolph's most-loved abstract strategy game (1962). Different mechanic from Only Knights — you connect opposite edges with a chain of knight-length pegs — but the same designer's instinct for clean rules and deep decisions. If you like this site's slot for strategy games, Twixt is the book-length version.
• New Ideas in Chess — Larry Evans The classic introduction to strategic thinking about chess positions — space, mobility, tempo, the pawn structure. Only Knights uses the knight's move and nothing else, but the chapters on mobility and space are pure transferable strategy-game literacy.
• Abstract strategy game collection (GIPF, Hive, Onitama) If knight-isolation is your entry point, these three are the natural next games. Hive plays with hex-grid movement, GIPF is about sliding markers off a hex board, and Onitama is a two-knight-and-three-pawn miniature chess variant with swapping move-cards. All three teach "read the position, not the piece."