Metisse

Metisse is a 2.5D desktop environment. More specifically, it is a X window manager with many features that set it apart from the traditional 3D "cube" workspace. Windows can be turned 3 dimensionally in any direction, enabling the user to fit more windows onto a screen, and they can be scaled, all while remaining fully operational. The development team has avoided such effects as wobbly windows, giving functionality and productivity higher priority than eye candy.

Metisse is available for Linux, FreeBSD and Mac OS X as free and open-source software subject to the terms of the GNU General Public License (GPL).

The project has not been in active development since 2010.