Apparently the original idle game (according to wikipedia at least) although modern idle games are probably influenced by Cookie Clicker and others as well.
I've occasionally been tempted to play Idle Champions which seems similar.
Idle Champions is fun but the numerical scaling on that game is whacky. It only takes like a month before you're doing 1 googol (1^100) damage and little dwarves or gnolls or rats or whatever drop a similar amount of gold. They say it's to differentiate effectively between linear and exponential scaling, but the end result is just whacky.
It's the only game I've ever played where your damage output is most effectively measured by the size of its exponent
