Battlefield killed my interest in Kanpani.. was too much of a chore.
Likewise, Meltoria destroyed what interest I had in Hitsuji.
I just don't like Girls Kingdom. Angelic Saga is an unbalanced, rage-inducing mess. I never even tried Big Bang whatever.. doesn't appeal to me at all. I don't like tower defense, so Aegis is right out. I have no interest in the half-dozen caRdPGs. Osawari drove me away because of the silly edits on principle. I see they've since started reverting them, but I don't find the gameplay all that compelling either.
..so PPS is pretty much the only game on Nutaku I play. I'll probably give Quiz of Valkyrie a shot, but depending on the play and type of questions, that may fail to hold my interest as well.