I was a big fan of Frostpunk but Ixion is damn hard, I think I failed around the 3rd or 4th level 3 times before giving up? It's really easy to get into a cascade failures in that game and the space you have to build in is much smaller than it looks at first. That was before they added the easy mode though so maybe I'll try it again at some point.
Simplifying is really different from what they did which is completely alter characters, unnecessarily kill off characters, introduce new plots that didn't exist, etc. The Lord of the Rings movies, and the recent Dune movie both did a lot of that but are considered fantastic adaptations. Even Game of Thrones was an excellent adaptation for the first ~5 seasons and had huge mass market appeal while still being complex.