Twin is a text-mode window environment. It supports mouse and multiple windows, has a built-in terminal emulator and window manager, and can serve as display for client applications. Its retro look-and-feel comes with very modern features: it is best described as a VNC-like server, that can use a variety of displays - all with mouse support: from a plain text terminal, to a Linux console, to a full kde, gnome or X11 desktop.
Source code hosted at https://github.com/cosmos72/twin
Definitely the best (only?) window manager for the TTY that provides an X server-like experience. It has some bugs but overall works very well. I really hope this project hasn't died, I'd love to see the final version of this.