AntiLine4

[mtaktikos]

Hi friends,
have made a fork of Fairy-Stockfish to reverse the goal of connect-n games, i.e. who makes a line of n pieces loses the game.
Changes made:
In pieces.cpp line 2312: instead of:
result = mated_in(ply);
now:
result = mate_in(ply);

In evaluate.cpp line 1259 instead of
score +=
now:
score -=

And in variants.ini the variant cfour renamed to antiline4 (of course, the changes turn all connect-n games, including tic-tac-toe, to anti mode)
The strongest Anti-Line 4 until now I am aware of is Drop-It! from 1993, written by Adrian Millett.
Now, in 4 games this program was beaten by Fairy-Stockfish 4:0, finally after 28 years we have a new champion in this game variant. BTW with the power of Stockfish it appears that it is a second player win (Fairy-SF vs Fairy-SF), but Fairy-SF is for sure >1000 Elo stronger than the former champion and manages to win with both sides.
A zip file with SFAntiLine4 is attached here, for comparison purposes it contains also the Shareware Drop-It
AntiLine4.zip