The Zebra Settings menu

The way Zebra plays is determined by a number of parameters, each of which has a sub-menu of its own.
The Function sub-menu
These settings specify at what times Zebra will think and/or play, such as does Zebra play black or white.

The Search depth sub-menu
This is where you set the lookahead, the most important parameter. It specifies the maximum length of the move sequences WZebra considers. If the lookahead is 1, WZebra only considers the position which arises after its own move, but if it is e.g. 10, WZebra will try out sequences of up to ten moves from the current board position when looking for the best move.

The Time sub-menu
It is possible to let WZebra determine the lookahead itself by giving it a certain amount of time to use for the entire game. A word of warning: Even on very slow PCs and very little time allocated (say, 1 or 2 minutes for the entire game) WZebra plays a rather strong game.

The Book sub-menu
WZebra comes equipped with an opening book containing more than 400'000 positions from 35000 games, almost all of which were generated by letting Zebra play against itself. Disabling the opening book makes WZebra's play more predictable and considerably weaker, especially if the lookahead is low.

The Midgame sub-menu
In this menu you can control the amount of randomness used by WZebra by playing. With a lot of randomness, it is possible to make WZebra make blunders in the midgame, thus making it play a bit like human players.

The Position table sub-menu
When thinking, WZebra maintains a large table of positions it has considered. In time dependent games and games with large lookahead (14 moves or more) the size of this table starts to matter. A bigger position table will speed up the searches but will consume more system resources.