The realm rejoices as Paradox Interactive announces the launch of Crusader Kings III, the latest entry in the publisher’s grand strategy role-playing game franchise. Advisors may now jockey for positions of influence and adversaries should save their schemes for another day, because on this day Crusader Kings III can be purchased on Steam, the Paradox Store, and other major online retailers.
The collection should work if the demo works. Demos are rarely updated to match new OS, while the main game might actually be patched to make it work.
Yea, so the same thing applies if you buy it in a store - ask them first if it will work on your Win 7 computer and if you can return it if it doesn't work. Usually easier to find a person allowed to make such decisions if you contact the company by mail, since they can just not reply to your question until the right guy is in. If you visit a store that "right guy" has to be present while you are.
Please return here and share your findings - either way it will be good for others to have confirmation.
Thank you for the information, and hope you are enjoying the game