qubes os

A reasonably secure operating using compartmentalization

Screenshots

Hunter's comment

if your into running VM machines to try out new operating systems then Qubes might interest you because of it's virtualization features.

Qubes OS is a security-oriented operating system (OS). The OS is the software that runs all the other programs on a computer. Some examples of popular OSes are Microsoft Windows, Mac OS X, Android, and iOS. Qubes is free and open-source software (FOSS). This means that everyone is free to use, copy, and change the software in any way. It also means that the source code is openly available so others can contribute to and audit it.

Link

https://www.qubes-os.org/