Looks like a one game made 22 times :)
Vogel's games are based on a few different iterations of his in-house RPG game engines and he has remade/updated his most popular Exile/Avernum series in each generation of the game engine so some of them are very nearly the same game.
And they're fantastic. Dated looking and punishing but expansive and detailed and intricate.
I remember reading a post by Jeff were he mentions that instead of redoing all graphics and art in each new chapter of his series, he prefers adding content in other areas like gameplay and story, and his customers love that.
I like his games and have spent some money on them over the last 20 years, never regretted it.
They are not focused to appeal superficially visually. Someone who solely ranks games by polygon count would be horribly disappointed. Thats just not his market.
Not a very good comparison since most games do not look like this, while most written texts do. I'm not saying the games are bad anyway. I'm actually hyped to try them out.