Tremfusion has been updated with 64-bit support and also natively supports the new chat/name colours available on the Der Bunker servers.

Tremfusion should work on all 64-bit versions of macOS, including macOS Catalina. You can download Tremfusion here.

Extract the .zip file and move Tremfusion.app to your /Applications folder, it has all the files required to run the game.

If you have an x86-only Mac or a Mac with a PowerPC processor running at least Mac OS X 10.4, you'll want to use this file instead, which contains the universal binary release for Tremfusion. It will not run on macOS 10.15 or later.

GrangerHub also maintain a 64-bit only macOS client. Follow their guide to install it.