Trinity Desktop Environment is a fork of the KDE desktop environment version 3 branch, in much the same way MATE was a fork of GNOME version 2 branch. TDE is notable to me for it's speed, visual design, stability, and vast eco-system of well-designed and functional user software that is part of the KDE 3 environment.
You would think an independent fork of a 11+ year-old project would be dormant. TDE updates have been slow but steady, not unlike the far more popular XFCE. Lately there has been an uptick in interest in TDE. TDE applications are getting occasional updates. The development team just launched a new web-based translation tool to help translate strings in TDE into more languages.
The project makes official repositories available, with both stable and testing branches, for a handful of Linux distributions In my experience installing TDE is much smoother on Debian and derivatives than on Fedora, CentOS, or OpenSUSE. You have been warned.
Because TDE does not require systemd, it runs well on Devuan, the systemd-free Debian fork. I recommend installing a base Devuan image with XFCE, installing the TDE repositories (use the Debian stretch repo for Devuan ascii), installing TDE, and then once everything is working, removing the XFCE components.* If that makes you squeamish, give Q4OS's TDE version for a spin. It's not the default TDE experience but it's pretty close. Q4OS has useful custom tools to help get you up and running.
It strikes me how many hundreds of thousands of hours went into building the amazing KDE 3 environment ecosystem that was lost when KDE moved to 4 and then quickly to 5. And not just the UI but the software, including personal finance managers, entire office suites, and handy GUI utilities. LDXE and LXQt were all created to be lightweight desktop environments, but TDE is a lightweight desktop environment plus an entire catalog of great software.
Here is a glimpse at Trinity Desktop Environment:
This is TDE 14.0.7, the current rolling testing branch, on Devuan ascii running in Hyper-V.
* Perhaps this process may be worthy of it's own walkthrough at a later date.