Clicker Heroes was released in 2014 by Playsaurus, a small studio, and quickly became one of the defining games of the incremental/idle genre alongside Cookie Clicker. It took the "click to earn, spend to automate" loop and wrapped it in an RPG framework — instead of an abstract resource, you're defeating monsters and recruiting a roster of heroes, each with their own damage output and upgrade tree, to push further through an essentially endless progression of stages.
Its "ascension" system, which resets your progress in exchange for permanent bonuses that make the next run faster, became a hugely influential mechanic that countless later idle games borrowed and built upon — it's one of the clearest examples of a genre-defining design choice from this era of browser gaming.
There's no final stage to "complete" — the goal is continual progress, pushing your hero roster and damage output further with each ascension cycle, with the long-term satisfaction coming from how much faster each subsequent run becomes.
It's one of the genre-defining idle games, and the ascension loop remains genuinely satisfying more than a decade after release. GBK Games also has Cookie Clicker and AdVenture Capitalist for more of the incremental genre.