EmpCho owns the rights to Arduin, and they are working on a new version, "Arduin Bloody Arduin" -
https://empcho.com/free-stuff/
They have a free pdf of the "Compleat Arduin book 1" at the link. I've met the two owners Dave and George multiple times, great guys - said they got my back and gave me a free back scratcher branded with co. info and "We have your back!" lol On my desk right now, use all the time, pretty sturdy if can get your hands on one..
I joined the "Borrows and Borderlands" discord a few weeks back, they run online games there often of their "Game of Games", meaning using the "portal", they interoperate all these different systems together (somehow-not sure how it works), and have updated recently to include Shadowdark.
I didn't back, but Matt of B&B hand makes all those - boxes, prints and binding, they are pretty solid quality which intrigues me.. but don't have the cash, time or energy for another game currently.. as much as my buddy keeps trying to get me into it. (I don't know if he would do all of them, or continue to do so.. but has in the past. should say in the KS.)
I read Shadowdark rules, two in our group did the KS, neither wants to run; I was so-so, nothing really stood out or appealed to me.. if I only played and knew 5e, I can see that as a jumping off game, but so many other games out there that scratch the same itch that I own. I don't particularly care for the spell system, but I like the reimage of SD over DCC which annoyed the F out of me. Give me Vancian or give me another system!