Almost every book I read back when I was a school student.
Each month we had to read a boring book chosen by the school, and at the end of each month we had a annoying test with questions like: “When the protagonist discovered the truth, what was the emotion he felt?” Or “How did the author felt when writing this?” So I had to read 300 pages of a boring book and pay attention to each detail each month.
I don’t dislike reading, actually I enjoy good books, but reading something against my will is sickening.
Steam, I can install the Steam client without any problems on moat distros, also Valve has done a lot of things to make the Linux gaming better.
Gog doesn’t have a desktop app for Linux, they’re focused totally Windows so I don’t care about it.
If I want “DRM free” games, then I pay for the original version with DRM and then pirate it to play whenever I want.