When I'm not working on code to support my employers' Kubernetes centered environment, specifically automation code to ensure a number of clusters all serve the same base set of applications for customer onprem-installs, I enjoy exploring and coding for retro architectures, such as the Incompatible Time Sharing system for the PDP-10, the Nintendo Game Boy, Amiga 500, etc. I once built an emulator for a non-existing 8-bit computer of my own design, which I then programmed (with my own assembler) classic games like Sokoban for. I often play with electronics and microcontrollers (plain AVR, not Arduino because I'm of hipster reasons) where I've implemented a light weight TCP like protocol for RC car radio communication. My next project is probably going to be a Z80 based computer (built using original ICs, replacing EEPROM and PIO with a modern AVR microcontroller) that I wish to bootstrap into at least a Forth system somehow. For the complete retro feel, it will feature an Altair 8800-like front panel with switches and step programming.
I previously built a network automation engine and a vendor/device agnostic network device API, basically something like NAPALM, before I knew that project existed.