Matches come from the tags Steam players vote on each game, weighted so a rare tag counts for far more than one that sits on half the store. A game's popularity never moves it up this list.
The closest matches to Increlution on Steam are xiuzhen idle, 懒人修仙传2, Holyday City: Reloaded, Stuck In Time, Incremental Cubes. They rank highest because their Steam community tags overlap most with Increlution's — shared tags include Idler, Time Management, Clicker.
How are games like Increlution chosen?
Every game is described by the tags Steam players vote on it. Rare, specific tags such as Idler, Time Management, Clicker count far more than catch-all ones like "Indie" or "Singleplayer", and each game is scored on how closely its whole tag profile matches Increlution's. Popularity never affects the ranking.