This is the first release.
RAD-Doom is a port of Doom which is natively executed on the RAD Expansion Unit for the C64/C128 (which makes use of a on the Raspberry Pi Zero 2/3A+/3B+).
Where did you get your RAD? How to get one?
You've built it yourself? Cool, this project is for tinkerers!
If you have questions about assembling one, don't hesitate to ask!
If you can't build one yourself, there are official sellers of Sidekick64/RAD/SIDKick: www.restore-store.de (all three projects), www.retro-updates.com (Sidekick64).
It is also perfectly fine and appreciated if someone sells spare PCBs (populated or not) of a PCB-order or manufactures a small batch and offers them on a forum, but I expect the price tag to be lower than that of the aforementioned official sellers.
If you bought a Sidekick64/RAD/SIDKick for the same price or even more, this clearly is a violation of the license and you should ask the seller why they are not respecting open source/CC developers' licenses.