What do Alyx’ settings mean?

Alyx is a customizable AI character that we created. Unlike the others like Claire or Boris, you can tweak Alyx to alter her strength and play style.

There are currently ten parameters that you can alter. We tried to name them intuitively so as not to bore you with chess engine implementation details. Here are the basic descriptions:

  • Strength – this is the most important parameter. It specifies how many plies (half-moves) Alyx will think ahead. In some cases Alyx will think even more than this number, but this is the baseline. Increasing this value greatly increases the required time.
  • Time – this is the allocated time per move. It can be as low as 1 second and as high as 4 minutes per move. It should be high enough so that Alyx has enough time to finish thinking. In other words, it’s not enough to increase strength, you should increase the time as well.
  • Judgement – This parameter affects Alyx’ ability to evaluate captures and recaptures when thinking, in order to arrive at a ‘quiet’ position before evaluating the board. Chess engines call this quiescence.
  • Accuracy – This is the accuracy in evaluating the board. Increasing this to 100% makes Alyx always perform the best move; lower values allow for more variation in play. Decreasing this will lead to spectacular blunders.
  • Focus – You shouldn’t need to alter it too much. The impact on search is relatively limited. Lowering it can make most searches faster, with an occasional very slow one. Higher values will make search times more uniform. Technically known as ‘aspiration window‘.
  • Aggressivity controls how ‘desirable’ captures may seem. A higher value doesn’t mean a stronger play!
  • Memory – how much memory is allocated for ‘cache’ – remembering old positions. Higher values will improve search times, but only up to a point.
  • Intuition controls the heuristic algorithms, helping Alyx remember previous moves that were very good/bad. Altering it will subtly change the behavior, but there’s no a specific direction that will increase the strength. You’ll have to experiment.
  • Insight is important in discarding bad moves. Moving it all the way to the left will possibly lead to more accurate results since no move will be discarded in tricky situations, but will dramatically increase search times.
  • Knowledge affects openings and determines how much Alyx will rely on her memorized opening lines.

If you find an interesting combination of parameters, please share with us!