Zapling Bygone's tentacly skull-stealing hivemind is... kind of neat?
"Metroidvania" is a terrible phrase that gets in the way of its own definition and I hate it.
It does, however, still apply to Zapling Bygone. Describing it in less mechanical terms could make it sound creepy. You're a spore of an all-consuming hivemind, dropped on an unfamiliar planet to assimilate it. You move by skittering about on wobbly green tentacles, leaping and climbing and clinging and lashing out at living things with them, then absorbing the green muck that bursts out, and periodically consuming a creature powerful enough to be worth assimilating. And wearing its skull in the centre of your tentacle mass, because why not.