Full Report for Othellito by Jonas Lidström Isegrim

Full Report for Othellito by Jonas Lidström Isegrim

Generated at 20/05/2020, 21:00 from 1000 logged games.


Start Position

The grid

The four by four (4x4) invisible and floating grid is formed by the cards placed and may shift during play. Players must place their card adjacent next to another card on the board, orthogonally or diagonally.


Players (starting with black) take turns, placing cards of their assigned colour on the board. During a play, any cards of the opponent's colour that are in a straight line and bounded by the card just placed and another card of the current player's colour are turned over to the current player's colour.

Each turn, you must flip at least one card.

Clear a column or row

If you place a card so there is a fifth row or column, you must remove the opposite row or column; however, you may not remove a row or column containing more cards than you just flipped. If you cannot do so, the play is illegal.


The game ends when a player has no legal moves.

The player with most of their own colour facing up wins. Ties are possible.


General comments:

Play: Combinatorial

Family: Combinatorial 2019,Minimal

Mechanism(s): No Board,Scoring

Level: Standard

BGG Stats

BGG EntryOthellito
BGG Rating8.11111
BGG Weight1

BGG Ratings and Comments

xerossilence8This game is so clever for how simple it is. It's amazing that this game hasn't been around about as long as Reversi/Othello. Same capture mechanic as Othello, but no board. You're collaboratively building a 4x4 board of cards, but you can add a fifth row or column if the number of captures matches or exceeds the number of cards on the far row or column, and if you do, that far row or column falls off the board. That twist from Othello makes for a really different game, since you don't have the walls and corners as goals. Best of all, with 18 cards, if you have a deck fo playing cards, you've got this game available to you. [tag B1 abstract]
whac3N/ACan play with equipment I own.

Kolomogorov Complexity Estimate

Size (bytes)26658
Reference Size10293

Ai Ai calculates the size of the implementation, and compares it to the Ai Ai implementation of the simplest possible game (which just fills the board). Note that this estimate may include some graphics and heuristics code as well as the game logic. See the wikipedia entry for more details.

Playout Complexity Estimate

Playouts per second14140.93 (70.72µs/playout)
Reference Size1308557.97 (0.76µs/playout)
Ratio (low is good)92.54

Tavener complexity: the heat generated by playing every possible instance of a game with a perfectly efficient programme. Since this is not possible to calculate, Ai Ai calculates the number of random playouts per second and compares it to the fastest non-trivial Ai Ai game (Connect 4). This ratio gives a practical indication of how complex the game is. Combine this with the computational state space, and you can get an idea of how strong the default (MCTS-based) AI will be.

Playout/Search Speed

LabelIts/sSDNodes/sSDGame lengthSD
Random playout15,519130610,8364,3023924

Random: 10 second warmup for the hotspot compiler. 100 trials of 1000ms each.

Other: 100 playouts, means calculated over the first 5 moves only to avoid distortion due to speedup at end of game.

Mirroring Strategies

Rotation (Half turn) lost each game as expected.
Reflection (X axis) lost each game as expected.
Reflection (Y axis) lost each game as expected.
Copy last move lost each game as expected.

Mirroring strategies attempt to copy the previous move. On first move, they will attempt to play in the centre. If neither of these are possible, they will pick a random move. Each entry represents a different form of copying; direct copy, reflection in either the X or Y axis, half-turn rotation.

Win % By Player (Bias)

1: Black win %52.20±3.10Includes draws = 50%
2: White win %47.80±3.08Includes draws = 50%
Draw %66.80Percentage of games where all players draw.
Decisive %33.20Percentage of games with a single winner.
Samples1000Quantity of logged games played

Note: that win/loss statistics may vary depending on thinking time (horizon effect, etc.), bad heuristics, bugs, and other factors, so should be taken with a pinch of salt. (Given perfect play, any game of pure skill will always end in the same result.)

Note: Ai Ai differentiates between states where all players draw or win or lose; this is mostly to support cooperative games.

Levels of Play

AIStrong WinsDrawsStrong Losses#GamesStrong Win%p1 Win%Game Length
Grand Unified UCT(U1-T,rSel=s, secs=0.01)36013797.3040.5426.11
Grand Unified UCT(U1-T,rSel=s, secs=0.07)232604973.4748.9862.29

Level of Play: Strong beats Weak 60% of the time (lower bound with 90% confidence).

Draw%, p1 win% and game length may give some indication of trends as AI strength increases; but be aware that the AI can introduce bias due to horizon effects, poor heuristics, etc.


Game length66.11 
Branching factor4.46 
Complexity10^40.59Based on game length and branching factor
Samples1000Quantity of logged games played

Computational complexity (where present) is an estimate of the game tree reachable through actual play. For each game in turn, Ai Ai marks the positions reached in a hashtable, then counts the number of new moves added to the table. Once all moves are applied, it treats this sequence as a geometric progression and calculates the sum as n-> infinity.

Move Classification

Distinct actions37Number of distinct moves (e.g. "e4") regardless of position in game tree
Good moves10A good move is selected by the AI more than the average
Bad moves26A bad move is selected by the AI less than the average
Samples1000Quantity of logged games played

Board Coverage

A mean of 65.55% of board locations were used per game.

Colour shows the frequency of visits.

Change in Material Per Turn

This chart is based on a single playout, and gives a feel for the change in material over the course of a game.


Table: branching factor per turn.

Action Types per Turn

This chart is based on a single playout, and gives a feel for the types of moves available over the course of a game.

Red: removal, Black: move, Blue: Add, Grey: pass, Purple: swap sides, Brown: other.


This chart shows the best move value with respect to the active player; the orange line represents the value of doing nothing (null move).

The lead changed on 44% of the game turns. Ai Ai found 36 critical turns (turns with only one good option).

Position Heatmap

This chart shows the relative temperature of all moves each turn. Colour range: black (worst), red, orange(even), yellow, white(best).

Good/Effective moves

MeasureAll playersPlayer 1Player 2
Mean % of effective moves81.5382.3780.69
Mean no. of effective moves4.094.243.95
Effective game space10^42.1110^21.5110^20.59
Mean % of good moves19.3425.6813.00
Mean no. of good moves0.951.220.68
Good move game space10^5.1710^4.2710^0.90

These figures were calculated over a single game.

An effective move is one with score 0.1 of the best move (including the best move). -1 (loss) <= score <= 1 (win)

A good move has a score > 0. Note that when there are no good moves, an multiplier of 1 is used for the game space calculation.

Quality Measures

Hot turns93.24%A hot turn is one where making a move is better than doing nothing.
Momentum25.68%% of turns where a player improved their score.
Correction52.70%% of turns where the score headed back towards equality.
Depth1.70%Difference in evaluation between a short and long search.
Drama0.00%How much the winner was behind before their final victory.
Foulup Factor59.46%Moves that looked better than the best move after a short search.
Surprising turns24.32%Turns that looked bad after a short search, but good after a long one.
Last lead change93.24%Distance through game when the lead changed for the last time.
Decisiveness2.70%Distance from the result being known to the end of the game.

These figures were calculated over a single game, and based on the measures of quality described in "Automatic Generation and Evaluation of Recombination Games" (Cameron Browne, 2007).



Opening Heatmap

Colour shows the success ratio of this play over the first 10moves; black < red < yellow < white.

Size shows the frequency this move is played.

Unique Positions Reachable at Depth


Note: most games do not take board rotation and reflection into consideration.
Multi-part turns could be treated as the same or different depth depending on the implementation.
Counts to depth N include all moves reachable at lower depths.
Inaccuracies may also exist due to hash collisions, but Ai Ai uses 64-bit hashes so these will be a very small fraction of a percentage point.

Shortest Game(s)


10 solutions found at depth 6.



White to win in 10 moves

White to win in 5 moves

Selection criteria: first move must be unique, and not forced to avoid losing. Beyond that, Puzzles will be rated by the product of [total move]/[best moves] at each step, and the best puzzles selected.