WWIV 5.0 Alpha/Beta has built in Telnet support. Not sure how you can sign up for a Alpha/Beta test of it. WWIV 4.30 is the latest commercial release but needs a FOSSIL Telnet driver like NetModem or Com/IP to work right. Synchronet reminds me of a WWIV clone. WWIV 4.30 is DOS based, so it is picky about the OS it runs under. You may have to trick it to work with W2K or XP or Windows 2003.
WWIV download and information can be found at:
http://wss.wwiv.com/
WWIV 4.30 can run with GameSrv for free, but I have yet to get online games to work with it. TW2002 expects a modem port in the FOSSIL driver and NetFoss doesn't emulate com ports.
http://www.mannsoft.ca/howto-wwiv-gamesrv.html
Download WWIV 4.30 unregistered and you will have only 1 instance, then use GameSrv with it on a different port than your current BBS and try to log into it from another machine and play games. Don't register it unless you can get it to work.
Telnet to skulls.sytes.net Skull and Crossbones and tell the SYSOP there that "Cable" sent you. That is my handle on his BBS. He was very helpful in getting me GameSrv. He runs WWIV 5.0 and it works like a champ.
Also check with
http://www.exciter.ws port 23 they have Synchronet BBS with TWGS support. Ask the SYSOPS how they did it. Maybe they can help you.
Good luck!