Full Report for Yodd by Luis Bolaños Mures

Full Report for Yodd by Luis Bolaños Mures

Yodd is an elegant connection and territory game for two players.



A group is a set of connected, like-colored stones. A single stone is also a group.


Starting with Black, players take turns placing one or two stones of any color on empty points. On his first turn, Black can only place one stone.

At the end of each turn, there must be an odd number of groups on the board (i.e. the sum of the number of Black and White groups must be an odd number).

Players can pass their turn at any moment, unless it violates the previous rule (this means Black can't pass on his first turn).

When both players pass in succession, the game ends. The player with the fewest groups on the board wins.


General comments:

Play: Combinatorial

Family: Combinatorial 2012

Mechanism(s): Territory

Components: Board

BGG Stats

BGG EntryYodd
BGG Rating7.32143
BGG Weight2

BGG Ratings and Comments

luigi879My game.
ZickzackN/AElegant and innovative rules, would like to know more about gameplay
rayzg7.5It feels like a connection game where you get to place your opponent's goals! Ensuring that there's always an odd number of groups would be really, really, really annoying to play unless you're playing with a computer UI. It lost some ratings points because of that.
CoreyClark10MY GOD this game is deep. This is possibly a bigger happy accident than Go.
milomilo122N/AI've now played Yodd twice, and it's square-board analogue, Xodd, once. I much prefer Yodd. Impressions so far: First, the game's concept is more than a little intriguing. It's so coherent and simple and sensible that you can't believe no one's thought of it before, which to me is the hallmark of a beautiful idea - the inventor deserves high recognition for this. Staying connected across the center is important, since it allows you to keep your groups better connected. On the other hand, there's also incentive to build structures one or two rows away from the edges, because you can build "cages" for opponent stones there most easily. If it turns out that there's good balance between these two themes, Yodd could be a great game. As it is, my early impressions are positive. I discovered some interesting, unusual tactics immediately and some strategy considerations revealed themselves readily. There was no "I'm totally lost" feeling from which so many abstracts suffer. All to the good. If there's anything that annoyed me, it's that you need to keep track of how many groups, or even better, how many virtual groups both you and your opponent have, and it's hard to do, and I found myself recounting frequently. Maybe some kind of score track could remove this issue. On the other hand, only the difference in group number need be tracked really, so maybe this would become effortless with additional play.
King Lear10Yodd is amazing beautiful game. I am always up to a good game of Yodd at igGamesCenter!
orangeblood7Another enjoyable design from Luis Bolaños Mures. My appreciation for Yodd really shot up after playing against strong competition on a size 8 hex. There is very interesting board-wide strategy on larger boards.
m-s-voss8Playing on self made board using "Go" pieces. A good abstract game. Similar to "Xodd".
grasa_total5The consequences of the "odd number of groups" rule seem to run deeper than I was able to see in one play. My total flop of an opening game (on IGGC) was described by one onlooker as "oh I've seen this strategy before" even though, like, actually I just had no idea what I was doing.
russ8This and the square-board version Xodd are both cool clever games. A practical problem occurs if there are many groups in play: sometimes we don't notice that the number of groups has accidentally/illegally become even. For that reason I recommend saying "3 4" or whatever after each turn, to consciously confirm the current number of groups each side has.
pezpimp7.5Based on one play: Similar mechanics to a linking game where you have to connect both sides, however in this one you must have the least amount of groups of pieces, thus you want to link them all together. You can pass at anytime and you can play your opponents pieces which is really infuriating but a great mechanic. There must also always be an odd amount of sets on the board, combined for both players, taking that into account you can't simply connect or add pieces since it would break that rule. Quite enjoyed it.

Levels of Play

AIStrong WinsDrawsStrong Losses#GamesStrong Win%p1 Win%Game Length
Grand Unified UCT(U1-T,rSel=s, secs=0.01)36023894.7471.05173.42
Grand Unified UCT(U1-T,rSel=s, secs=0.03)36084481.8252.27175.07
Grand Unified UCT(U1-T,rSel=s, secs=0.07)36044090.0050.00176.38
Grand Unified UCT(U1-T,rSel=s, secs=0.20)360036100.0033.33177.92

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.

Kolomogorov Complexity Estimate

Size (bytes)28579
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 second1415.53 (706.45µs/playout)
Reference Size955840.18 (1.05µs/playout)
Ratio (low is good)675.25

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.

Win % By Player (Bias)

1: Black win %49.40±3.09Includes draws = 50%
2: White win %50.60±3.10Includes 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.

Playout/Search Speed

LabelIts/sSDNodes/sSDGame lengthSD
Random playout1,4297246,7041,1381732

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.


Game length179.00 
Branching factor129.08 
Complexity10^345.45Based on game length and branching factor
Computational Complexity10^8.73Sample quality (100 best): 1.76
Samples1000Quantity of logged games played

Move Classification

Distinct actions339Number of distinct moves (e.g. "e4") regardless of position in game tree
Good moves50A good move is selected by the AI more than the average
Bad moves289A bad move is selected by the AI less than the average
Samples1000Quantity of logged games played

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.


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 12% of the game turns. Ai Ai found 0 critical turns (turns with only one good option).

Overall, this playout was 30.51% hot.

Position Heatmap

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


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.

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 2.