The original servers and development of game was terminated at 2013 October (first server shut down it the middle of October and the last 2 severs at the last day of October) and Windows 8.1 came same year, but sooner. So all Windows versions before Windows 10 should be good, but most recommended is Windows 7 or Windows XP (if very week and old PC) for this game at this moment.
When last time I talked about New Client with you, you said at best work with New Client continue near end of this year and and chance of New Client releasing in 2022 is like 50/50, so now I'm a bit confused for moment.
got it! Thank U!