Not everyone is in the veteran asshole clique that appears to dominate this site, so this is offered to anyone new to gaming who is unfortunate enough to stumble across this cesspool.
Gog.com, source of older computer games at bargain prices. I've never encountered any that would not run just fine on a contemporary Windows operating system, regardless of age. Now slowly creeping into greed territory, selling newer and more expensive games as well as older classics. I can't reccomend their "Gog downloader" utility, you're better off manually downloading if that is still possible, been a while since I tried.
Boardspace.net, a free online site for playing abstract strategy games, some even have solo play capacity. This article points to some similar sites:
https://alternativeto.net/software/tabletopia/
BoardGameGeek, an extensive resource of information, covering nearly every board game ever made.
WayBackMachine can sometimes find things you thought were gone forever. https://archive.org/web/
If you are interested in game design, you might find "The Art of Game Design" a useful resource. It isnt' what I would call an inexpensive book, so you might consider checking to see if your library has a copy. If they don't, many libraries participate in some form of the Interlibrary Loan System; consult the reference librarian for assistance. I believe the book is available as a PDF as well as paper.
https://www.schellgames.com/art-of-game-design/