3 MB OPERATING SYSTEM

Kolibri desktop is a small 3 MB operating system
yes just 3mb
it is written in Machine Code (CPU language) and is not based in linux , windows or any other variants.

A huge number of applications are packed in this small Operating System. like games , tables editor , a compiler , a text editor , web browser and many more.
It also includes DOSBOX on which you can run every dos based game.