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 Human Resource Machine on Steam are 7 Billion Humans, SHENZHEN I/O, TIS-100, Turing Complete, SpaceChem. They rank highest because their Steam community tags overlap most with Human Resource Machine's, and shared tags include Programming, Education, Touch-Friendly.
How are games like Human Resource Machine chosen?
Every game is described by the tags Steam players vote on it. Rare, specific tags such as Programming, Education, Touch-Friendly count far more than catch-all ones like "Indie" or "Singleplayer", and each game is scored on how closely its whole tag profile matches Human Resource Machine's. Popularity never affects the ranking.