The issue can be reproduced on both Mac and windows 64 bit with jdk9 promotion build 122.
To reproduce:
1. Install mentioned build, enable trace and console in jcp and go to http://www.pogo.com
2. Click on the Sign In link at the top of the page, and use getjava10 / admin1234 as username/password
3.Click 'Backgammon'
4.Pick a room and play a game , such as Gold Ring Room
5. If The applet can not load and there's exception thrown in java console, the issue is reproduced.
The screenshot and trace are attached.