Set the knockback-friction value to 2.0 (vanilla) again and host UHCs. Many people stopped playing them because the knockback was terrible; apart from that your UHC was awesome. You should also try to host EU games again but promote them with EU YouTubers. Right now everyone is playing on SecondLife, an EU UHC server and - suprise, surprise - they have 100+ player fills and even had 500 player games. That server sucks terribly so it would be easy for you to regain your playerbase, trust me ^^ Rethink your thoughts on UHC, Physci and Jordan.