Telengard
Arcane
That's tough to definitively say. While Nancy Drew games sell shockingly lower than anything DeepOcean mentioned (downwards of a tenth), they're short games with a tight turnaround, allowing Her Interactive to have made a whole heck of a lot of them in a short space of time (much like the books they're based on). Mixed with a very loyal Mother/Daughter audience, there's money to be made there. Safe, trusted, fun children's brand kind of thing.then the 'real world' settings.
That's an interesting thing to say, given that the genre has become associated with Nancy Drew-type real world "girls' games". Perhaps that's an incorrect association.
It's the suite of games approach, which can make them seem like they're everywhere. But at the same time, they're nowhere near bestsellers, and not pretending to be.