A lot of old games have become unplayable on modern hardware and operating systems. I wrote an article about how making games open source will keep them playable far into the future.
I also discuss how making games open source could be beneficial to developers and companies.
Feedback and constructive criticism are most welcome, and in keeping with the open source spirit, I will give you credit if I make any edits based on your feedback.
Shoutout to Frictional Games (known for Penumbra, Amnesia, Soma) who publish many of their older (commercially successfully) games on their GitHub: https://github.com/FrictionalGames