Awesome

ElmOthello

the well known Othello game using Elm

<a href='http://carstenkoenig.github.io/ElmOthello' target='_blank'></a>

You can play the game here

Basics

All the basic modelling is inside the Othello module and Main implements some very basic display using Divs with columns of Svg elements (TODO add turn animations of some sort).

The game right now assumes White (first player) to be the human and moves the black computer-AI right after (as I could not figure out if or how I can do long-running background processing with a Task or something similar).

AI

The AI is based on version of the Minimax algorithm implemented in the MiniMax module.

The heuristic used in there is based on a very simple positional evaluation (implemented in the AI module) - basically it values the corners very high, the cells around the corner very low (indeed negative), all the edges and the center cells high, ...

coordValues =
    [ [ 10, -5, 6, 5, 5, 6, -5, 10 ]
    , [ -5, -8, -4, -4, -4, -4, -8, -5 ]
    , [ 6, -4, 2, 3, 3, 2, -4, 6 ]
    , [ 5, -4, 3, 4, 4, 3, -4, 6 ]
    , [ 5, -4, 3, 4, 4, 3, -4, 6 ]
    , [ 6, -4, 2, 3, 3, 2, -4, 6 ]
    , [ -5, -8, -4, -4, -4, -4, -8, -5 ]
    , [ 10, -5, 6, 5, 5, 6, -5, 10 ]
    ]

and will evaluate the algorithm to a depth of 3 (which yields quick answer times but is not really hard to beat).

If you want a stronger AI you probably will have to add some advanced strategy like valuing stone-count more at the end of the game, valuing possible move-counts, pref switching few stones at the beginning etc.

It's a fun task to make those algorithms better.

Of course you can try to implement alpha-beta prunning too - which I might or might not do myself in the future.