Full Report for Xerz by Haya Miyamoto

Full Report for Xerz by Haya Miyamoto

Xerz is a two-player abstract strategy game, in which players move pawns in order to trap a pawn. The twist is, players share all the pawns, so trying to trap a pawn willy-nilly can backfire!

Generated at 2023-06-25, 02:40 from 1000 logged games.

Rules

Representative game (in the sense of being of mean length). Wherever you see the 'representative game' referred to in later sections, this is it!

How to Win

The last player to complete a turn wins. In other words, you win if you move a pawn so that your opponent wouldn’t be able to move the pawn to an empty space (you win before they get the next turn).

Play

Starting with White, players take alternate turns.

On your turn, build a pillar, and then move the pawn of the active color to an empty space. The color of that space is the next active color (= the color of the pawn your opponent must move on the next turn).

Building a Pillar

At the beginning of your turn, the space the active pawn is on becomes a pillar. This pillar is of your color (white or black) with a symbol of the active color (blue, green, violet, or red).

Once placed on the board, pillars can never be moved or removed.

Moving a Pawn

On your turn, after placing a pillar, you must move the pawn of the active color, following the these rules:

Miscellaneous

General comments:

Play: Combinatorial

Family: Combinatorial 2022

Mechanism(s): Shrinking Board,Stalemate,Territory

Components: Board

Level: Standard

BGG Stats

BGG EntryXerz
BGG Rating7.5
#Voters2
SD1.5
BGG Weight0
#Voters0
Year2022

BGG Ratings and Comments

UserRatingComment
hiimjosh6Interesting abstract that reminds me of a mix between LYNGK and Kamisado. You are trying to be the last player with a move. You create passages which only you can move pieces through. The game uses colored spaces which you move pieces to to determine which piece your opponent must move. It's weird. The rulebook is a mess, but it was fun. Would play again. Label: Good But Not Great
onoborisan9Early game strategy is unclear, but I love that it's non-loopy.

Kolomogorov Complexity Analysis

Size (bytes)17247
Reference Size10673
Ratio1.62

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 second51160.84 (19.55µs/playout)
Reference Size576535.02 (1.73µs/playout)
Ratio (low is good)11.27

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.

State Space Complexity

% new positions/bucket

State Space Complexity66560091 
State Space Complexity bounds63919838 < 66560091 < ∞ 
State Space Complexity (log 10)7.82 
State Space Complexity bounds (log 10)7.81 <= 7.82 <= ∞ 
Samples1931866 
Confidence0.000: totally unreliable, 100: perfect

State space complexity (where present) is an estimate of the number of distinct game tree reachable through actual play. Over a series of random games, Ai Ai checks each position to see if it is new, or a repeat of a previous position and keeps a total for each game. As the number of games increase, the quantity of new positions seen per game decreases. These games are then partitioned into a number of buckets, and if certain conditions are met, Ai Ai treats the number in each bucket as the start of a strictly decreasing geometric sequence and sums it to estimate the total state space. The accuracy is calculated as 1-[end bucket count]/[starting bucklet count]

Playout/Search Speed

LabelIts/sSDNodes/sSDGame lengthSD
Random playout51,6871991,936,8827,116378
search.UCT53,0081,946408

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: White win %50.80±3.10Includes draws = 50%
2: Black win %49.20±3.09Includes draws = 50%
Draw %0.00Percentage of games where all players draw.
Decisive %100.00Percentage 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.

UCT Skill Chains

MatchAIStrong WinsDrawsStrong Losses#GamesStrong Scorep1 Win%Draw%p2 Win%Game Length
0Random         
1UCT (its=2)63103239540.6308 <= 0.6614 <= 0.690849.690.0050.3137.18
5UCT (its=6)63103619920.6057 <= 0.6361 <= 0.665553.530.0046.4737.20
13UCT (its=14)63103669970.6025 <= 0.6329 <= 0.662350.550.0049.4536.44
17UCT (its=46)63101958260.7338 <= 0.7639 <= 0.791652.300.0047.7034.91
18UCT (its=126)63102658960.6735 <= 0.7042 <= 0.733245.650.0054.3535.09
19UCT (its=341)63102859160.6581 <= 0.6889 <= 0.718049.890.0050.1134.83
20UCT (its=928)63102999300.6478 <= 0.6785 <= 0.707750.110.0049.8935.55
21UCT (its=2523)63102538840.6831 <= 0.7138 <= 0.742652.380.0047.6235.99
22UCT (its=6858)63102628930.6759 <= 0.7066 <= 0.735552.410.0047.5936.73
23
UCT (its=6858)
510
0
490
1000
0.4790 <= 0.5100 <= 0.5409
48.40
0.00
51.60
37.78

Search for levels ended: time limit reached.

Level of Play: Strong beats Weak 60% of the time (lower bound with 95% confidence).

Draw%, p1 win% and game length may give some indication of trends as AI strength increases.

1st Player Win Ratios by Playing Strength

This chart shows the win(green)/draw(black)/loss(red) percentages, as UCT play strength increases. Note that for most games, the top playing strength show here will be distinctly below human standard.

Complexity

Game length40.40 
Branching factor13.33 
Complexity10^40.06Based 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

Board Size64Quantity of distinct board cells
Distinct actions136245Quantity of distinct moves (e.g. "e4") regardless of position in game tree
Killer moves6054A 'killer' move is selected by the AI more than 50% of the time
Too many killers to list.
Good moves12893A good move is selected by the AI more than the average
Bad moves123194A bad move is selected by the AI less than the average
Terrible moves121883A terrible move is never selected by the AI
Too many terrible moves to list.
Response distance%50.90%Distance from move to response / maximum board distance; a low value suggests a game is tactical rather than strategic.
Samples1000Quantity of logged games played

Board Coverage

A mean of 69.38% of board locations were used per game.

Colour and size show the frequency of visits.

Game Length

Game length frequencies.

Mean40.40
Mode[44]
Median42.0

Change in Material Per Turn

Mean change in material/round0.38Complete round of play (all players)

This chart is based on a single representative* playout, and gives a feel for the change in material over the course of a game. (* Representative in the sense that it is close to the mean length.)

Actions/turn

Table: branching factor per turn, based on a single representative* game. (* Representative in the sense that it is close to the mean game length.)

Action Types per Turn

This chart is based on a single representative* game, and gives a feel for the types of moves available throughout that game. (* Representative in the sense that it is close to the mean game length.)

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

Trajectory

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 52% of the game turns. Ai Ai found 11 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 moves73.2781.5564.99
Mean no. of effective moves9.8811.708.05
Effective game space10^33.1210^19.4410^13.67
Mean % of good moves16.4613.9518.96
Mean no. of good moves1.571.951.20
Good move game space10^6.8210^4.1810^2.64

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

MeasureValueDescription
Hot turns72.50%A hot turn is one where making a move is better than doing nothing.
Momentum27.50%% of turns where a player improved their score.
Correction40.00%% of turns where the score headed back towards equality.
Depth2.66%Difference in evaluation between a short and long search.
Drama0.42%How much the winner was behind before their final victory.
Foulup Factor35.00%Moves that looked better than the best move after a short search.
Surprising turns5.00%Turns that looked bad after a short search, but good after a long one.
Last lead change72.50%Distance through game when the lead changed for the last time.
Decisiveness25.00%Distance from the result being known to the end of the game.

These figures were calculated over a single representative* game, and based on the measures of quality described in "Automatic Generation and Evaluation of Recombination Games" (Cameron Browne, 2007). (* Representative, in the sense that it is close to the mean game length.)

Openings

MovesAnimation
f1-f7,h6-h4,c8-e8,a3-h3,h4-e4
f1-f7,h6-h4,c8-e8,a3-h3
f1-h1,h6-c6,a3-e3,h1-h5
f1-c4,a3-c1,c4-g8
f1-c4,a3-a1,c4-e4
f1-b5,h6-h8,c8-a8
f1-b5,h6-d2,c8-c5
f1-b5,h6-e6,a3-c5
f1-f3,h6-d2,c8-f5
f1-f3,h6-c1,f3-b3
f1-f4,c8-f5,h6-a6
f1-f5,h6-c1,f5-h3

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

0123456
1173035728105337194471734002746

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)

            

96 solutions found at depth 5.

Puzzles

PuzzleSolution

Black to win in 23 moves

White to win in 23 moves

Black to win in 21 moves

White to win in 23 moves

White to win in 19 moves

White to win in 21 moves

White to win in 19 moves

White to win in 21 moves

White to win in 19 moves

Black to win in 19 moves

White to win in 17 moves

Black to win in 13 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.