Microlandia - The Brutally honest city builder.
I started making this game several years ago, sporadically, abandoning it for month-long periods, but after posting it here a few times in Show NH I got the encouragement I needed to publish it to itch.io, then to Steam.
This month it crossed the $500/month mark by far, but it was a long road to get it to a state where it can actually be an interesting enough game to make money.