Lunacid is awesome - old-school dungeon crawling with slick controls. The speed and smoothness makes fighting all the old enemies new again.
The Kings Field games are... very hard to love. They're old-school dungeon crawlers with the most awful, clunky controls that you can imagine. They're all "pre-Miyazaki" FromSoftware games; don't expect many Souls-like touches. Getting killed by a skeleton because you can't turn round to face it in time, or falling down a hole because judging how far you've walked forward is difficult? Far more likely.
A Lunacid follow-up with a little more Ultima / Wizardry about it would be amazing. Bit more environmental variety, a few more RPG trappings, and for the love of all that is holy, a minimap. But I can't see how that would be better done in Sword Of Moonlight rather than just adding them to their existing engine.
The real advantage of a 120 Hz screen is that you get a much more graceful degradation if you dip below your fps target for a bit. If you're targeting 30 fps but drop to 25, it still feels pretty smooth on a high-refresh screen, whereas that's appallingly clunky on a low-refresh one. A "poor man's gsync", if you will.