@𝔭𝔶𝔯𝔞𝔱𝔢 @m0xEE @Machismo @pistolero @Nozakero 
Inferno from Vita Nuova, it's a small os meant for embedded applications, it's written in a language called Limbo which is interpreted with a virtual machine.  It's pretty interesting but hasn't really been developed in a long while.