So yeah, a SMT thread. As much as I enjoyed Shin Megami Tensei IV and (the improved) Shin Megami Tensei IV Apocalypse, I really do think that Shin Megami Tensei III: Lucifer's Call is one of the best games in the entire series. Hell, it's one of the best PS2 games, period.
The Magatama system is so intunitive and the demon fusing system while kinda flawed (SMT 4's system is far better because you can actually choose demon skills) also allows you to create many demons (try fusing Metatron without a guide or navigating the Labyrinth of Amala).

The morality choices are also better. Instead of the tired Law/Neutral/Chaos, you have several ideologies to side with, though you can choose to go neutral (Freedom/Demon endings) or just side with Lucifer like I did on my first playthrough (True Demon Ending). If anything, I consider the fight with Lucifer to be one of the best fights in the entire game.

Aren't the Demikids games related to this?

I suppose? The SMT series is pretty vast, considering all the spinoffs it has.

And now there's gonna be a Persona 5 gacha game. T_T

Considering that the Persona games have had dancing game spinoffs, and that Persona 5 is currently Altus's golden cow,  it's no surprise that Atlus needed to milk Persona 5 some more before they moved onto Persona 6.