ILLEGAL: n h8-f7 on turn 4:
There was no n on h8. The piece on h8 is a a.
Go back with your browser's BACK button, reload the page, and try again.
For diagnostic purposes, here is the full movelist:
1. P d2-d4 
1... p e7-e6 
2. P c2-c4 
2... p f7-f5 
3. A e1-d3 
3... dh d8-f6 
4. P e2-e3 
4... n h8-f7 
5. N f1-g3 
5... p g7-g6 
6. C a1-c2 
6... p a7-a5 
7. P e3-e4 
7... a c8-a7 
8. P e4-e5 
8... dh f6-g7 
9. DH d1-f3 
9... p d7-d6 
10. P b2-b4 
10... p a5-a4 
11. S b1-c3 
11... p d6-e5 
12. P d4-e5 
12... n f7-e5 
13. Q c1-a3 
13... n e5-d3 
14. S c3-d3 
14... a a7-c8 
15. R g1-e1 
15... k f8-f7 
16. C c2-e2 
16... s e8-c4 //e8-c6-c4
17. Q a3-c1 
17... s c4-c1 //c4-f4-c1
18. resign
In case there is a bug in the code, the settings file can be edited at /play/pbm/play.php?game=Cetran+Chess+2&settings=asymmetric&submit=Edit