Due to the recent unfortunate news about Terry Davis, I'll be hosting a backup of TempleOS (downloaded from the main site Sept 1 2018) here:
http://ifcfqq3cwrr74v6q.onion/content/temple_os/
Someone should write a serial console and serial modem telephone BBS program for Temple OS and it will become instantly viable as a modern 64 bit Commodore 64 replacement. Make Temple OS work with a US Robotics 56K Fax Modem over serial COMM port and we're in business.
The main problem I have with the OS concept was in choosing x86_64 as the development platform, good intention but naive. I've booted it on bare metal to try it out, spent 2 hours with it and haven't revisited. It's a good start, something to build off of.
Shrine OS looks like an interesting fork.
https://github.com/minexew/Shrine
TempleOS Mirror
https://github.com/minexew/TempleOS
https://github.com/codepony/templeos
http://www.templeos.org/