It's constantly changing tbh, so I've completely dismissed the notion of maintaining a "favorite game". That said, If I were forced to pick one right now, It would likely be Cosy Cafe.
Back in the day, the spell game got busted using real porn and a bunch of porn stars went after the game. Honestly shocking it hasn't happened again... Likely because no other game makes as much money.
Also, I hate real porn in games, but I do play html games sometimes.
NTR, Japanese Game and real porn.
I also frequently ignore lesbian, sex toys and femdom. However, it's difficult to avoid these tags because of how common they are.
Depends on definition and nation of origin. In the past, Patreon used to show how much money a project made. I remember seeing some of the larger projects making 20k USD a month. Obviously, that's great. But, it's likely the extreme minority.
Most devs are likely only making some extra pocket...