I had the Soldier of Fortune original game disk, but lost the box with the CD key. Mailed the devs/publishers asking for help, sending a picture of the disks, and they basically told me that I should have been more careful. Googled “soldier of fortune CD key” and ended up on one of those now-defunct websites which collected cracks and CD keys, discovering that not only you didn’t need the key, but you could also just download free stuff.
Now I pay for Prime Video, Netflix and Spotify and buy lots of games on steam/gog, but I also created an app used by thousands of people every month to help them sail the four seas
Yeah I can confirm it runs perfectly on the steam deck