Not to nitpick, but the "free" version of Doom is the shareware version, which contains only one episode (out of three in original game and four in ultimate doo

Not to nitpick, but the "free" version of Doom is the shareware version, which contains only one episode (out of three in original game and four in ultimate doom). And the shareware version was always free, even during it's original launch in 1994. I think these days a better example are free to play games such as League of Legends or Call of Duty Warzone, which can be played for years without paying a dollar.