$i is 1
Array
(
    [0] => swap
    [1] => f7-f6
)
ILLEGAL: n e7-f5;swap f7-f6 on turn 17:
The swap command does not have enough arguments.
Go back with your browser's BACK button, reload the page, and try again.
For diagnostic purposes, here is the full movelist:
1. d2-d4; swap d5 d4 
1... p e8-e6;swap e6 e5 
2. e2-e4;e6-e7 
2... p d8-d6;d4-d3 
3. g1-f3;e7-e8 
3... n g9-f7;d3-d2 
4. f1-d3;d2-e2 
4... n b9-c7;e8-d8 
5. b1-c3;e2-e3 
5... b f9-e8;b5-c5 
6. e1-g1;h1-f1;swap f3 e3 
6... n c7-d5;swap c5 d5 
7. e3-f5;b4-b5 
7... k e9-g9; r h9-f9; d5-d4 
8. c3-d5;d4-c4 
8... p c8-c7;g4-f4 
9. c1-e3;b6-b7 
9... n c5-e6;b7-a7 
10. a2-a4;f3-g3 
10... b e8-c6;swap a8 a7 
11. d1-g4;g6-f6 
11... b c6-d5;swap f6 e6 
12. e4-d5; swap g4 g3 
12... p b8-b7;swap a8 a9 
13. b2-b4; swap b4 b5 
13... p b7-b6;c4-c5 
14. c2-c4;c5-c6 
14... n f6-h5;e6-f6 
15. g3-h4;g4-g6 
15... h5-g7;swap g6 g7 
16. h4-h5;d8-e8 
16... n g6-e7;swap f6 f7 
17. a1-a3;swap g5 h5 
17... n e7-f5;swap f7-f6 
18. d3-f5;f7-e7 
18... n f6-d7;e7-e6 
19. f1-e1;e8-d8 
19... n d7-e9;d8-c8 
20. f5-g6;swap h5 g5 
20... p h8-h7;g7-f7 
21. g6-h7;e6-e7 
21... p g8-h7;e7-g7 
22. h5-h7;f4-f5 
22... n e9-g8;g7-g6 
23. e3-b6;swap b6 c6 
23... b c9-f6 
24. c6-a8; a9-b9 
24... resign // - wdtr2 has resigned. -
In case there is a bug in the code, the settings file can be edited at /play/pbm/play.php?game=EIGHT-STONE+CHESS&settings=default&submit=Edit