I got this game - Aquaria
from a friend and it reminded me of old vision that i had when i re-watched Ocean Girl. Almost same setting, and almost the same character.
Game is about a girl who lives alone in underwater world called Aquaria and then something happens and...
Plot line is completely different from Ocean Girl but there are moments that could be taken from OG or could be used in this new OG series.
Game has playable demo so you may try it out. And even if it does not fit into OG i still recommend it.