Full Report for Genius Loci by Stephen Tavener

Full Report for Genius Loci by Stephen Tavener

An activator game, with combos

Generated at 09/10/2020, 17:59 from 19234 logged games.


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

Move/select a spirit, then make a sacrifice (capture) with a man according to the rules for that spirit.
So long as you keep using the same man to sacrifice, you may keep activating other spirits; however no spirit can be activated more than once per turn. Note that you may sacrifice your own pieces.
Spirits move any distance in a straight line; they may move over occupied spaces, but must end in an empty space. Spirits move men as follows:
Saltator (↷): Jump over Saltator, landing the same distance on the opposite side.
Pulsor (→): Move one space directly away from Pulsor
Tractor (⤙): Move one space directly towards Tractor
Scylla (⟳): Move one space clockwise around Scylla
Charybdis (⟲): Move one space anticlockwise around Charybdis

To activate a god, click on that god (or drag the god to its destination square if you want to move it). The god will now be highlighted in orange. Now choose a man which can move, and make a capture according the the god's rules; that man will change to a cross to indicate that he is now the high priest (only piece to move this turn). Continue activating gods and moving the high priest until you have either activated all gods, or choose to pass.


General comments:

Play: Combinatorial,Themed

Family: Combinatorial 2014

Mechanism(s): Capture,Movement,Variable Powers

Components: Board

BGG Stats

BGG EntryGenius Loci
BGG Rating6.6875
BGG Weight2

BGG Ratings and Comments

grasa_total5I feel like there's a puzzle here I couldn't solve, which is: what to do after a few moves when the middle's hollowed out and now all the pieces are stuck around the edge of the board, but the spirits are all in each other's way so you don't have many choices. Quantum Leap (a very similar "every move must capture" game on the surface) has tons of options at first, and the cooling down to a quiet board is gentle and slow. In Genius Loci, that cooldown seemed sudden and felt bad; suddenly I have few choices, or I have no choice at all but to destroy one of my own pieces, or I have a bunch of pieces that are already dead unless I execute a three-move sequence which depends on you making a mistake. So like I said, I wonder whether I missed some new opportunities that phase of the game provided. I bet that in about a year, I'll look at this, realize I haven't been tempted to play again, and lower my rating retroactively. But who knows! [Update: That happened in two months instead. But it could go up if I do feel the urge to play again. Who knows?]
mrraow10My game :) This is a combinatorial game where player pieces are only able to move if doing so allows a sacrifice to one of the spirits (neutral pieces). Multiple combos abound, if you have the wits to find them! Design Notes (also in rulebook): This game is inspired by the "Activator Piece" discussions in the BGG abstract games forums. This is the purest game I could devise – the men do not move at all, unless an activator allows them to do so; the theme of spirits demanding sacrifices came naturally from the mechanics. Activator games seem to be inherently lacking in clarity. I actually started with around 10 powers, but quickly discarded half of them as being too confusing. Even then, the first incarnations of the clockwise/anticlockwise spirits acted at any distance; and had to be severely restricted to improve game play. Note you can now play against the AI.
Kaffedrake4This is frightfully opaque: each turn can involve from one up to ten piece moves, and properly evaluating a turn means having to read as many steps forward from each potential move sequence. A human just can't do that (although if you fool around and find a sequence that leaves you three pieces ahead, you can be [i]fairly[/i] sure it's to your advantage). Minor gripes: lack of graphical clarity and a vague sense of arbitrariness in the set of activator pieces.
fogus5.5Preliminary rating: An opaque abstract. More plays needed.
nestorgames9really good :)

Kolomogorov Complexity Analysis

Size (bytes)25994
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 second11829.78 (84.53µs/playout)
Reference Size290587.86 (3.44µs/playout)
Ratio (low is good)24.56

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 playout8054722695

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 %51.22±0.71Includes draws = 50%
2: Black win %48.78±0.71Includes draws = 50%
Draw %0.00Percentage of games where all players draw.
Decisive %100.00Percentage of games with a single winner.
Samples19234Quantity 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
1UCT (its=2)63103199500.6336 <= 0.6642 <= 0.693551.160.0048.8468.09
4UCT (its=5)63103409710.6193 <= 0.6498 <= 0.679248.090.0051.9167.95
5UCT (its=14)63103599900.6069 <= 0.6374 <= 0.666749.700.0050.3067.67
6UCT (its=37)63103169470.6357 <= 0.6663 <= 0.695652.270.0047.7366.92
7UCT (its=100)63102809110.6619 <= 0.6926 <= 0.721754.560.0045.4466.76
8UCT (its=273)63101938240.7357 <= 0.7658 <= 0.793453.520.0046.4866.12
9UCT (its=742)63102178480.7137 <= 0.7441 <= 0.772350.590.0049.4166.29
UCT (its=742)
0.4760 <= 0.5070 <= 0.5379

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.


Game length67.28 
Branching factor3.54 
Complexity10^22.86Based on game length and branching factor
Computational Complexity10^8.01Sample quality (100 best): 11.13
Samples19234Quantity 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 actions440Number of distinct moves (e.g. "e4") regardless of position in game tree
Killer moves28A 'killer' move is selected by the AI more than 50% of the time
Killers: g4-g2,d1-b3,e1-g1,a7-c7,d1-c2,g4-e6,a7-a5,g3-f4,g3-g2,e1-d1,a4-c2,b6-a6,e1-a5,g1-g3,b7-b5,a6-a4,d7-b7,c4-a4,c4-c2,d5-d7,c5-a5,c2-d1,e4-g4,e3-e1,d1-f1,e3-g3,c2-b3,f5-d7
Good moves243A good move is selected by the AI more than the average
Bad moves197A bad move is selected by the AI less than the average
Response distance1.64Mean distance between move and response; a low value relative to the board size may mean a game is tactical rather than strategic.
Samples19234Quantity of logged games played

Board Coverage

A mean of 95.91% of board locations were used per game.

Colour and size show the frequency of visits.

Game Length

Game length frequencies.


Change in Material Per Turn

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.)


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.


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 16% of the game turns. Ai Ai found 6 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 moves86.6689.1384.41
Mean no. of effective moves2.312.162.46
Effective game space10^15.8910^6.9910^8.90
Mean % of good moves36.5118.0053.44
Mean no. of good moves1.270.941.57
Good move game space10^8.8010^3.6410^5.16

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 turns61.19%A hot turn is one where making a move is better than doing nothing.
Momentum8.96%% of turns where a player improved their score.
Correction23.88%% of turns where the score headed back towards equality.
Depth5.34%Difference in evaluation between a short and long search.
Drama7.40%How much the winner was behind before their final victory.
Foulup Factor47.76%Moves that looked better than the best move after a short search.
Surprising turns2.99%Turns that looked bad after a short search, but good after a long one.
Last lead change73.13%Distance through game when the lead changed for the last time.
Decisiveness41.79%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.)

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)

No solutions found to depth 17.