Revive... Sosei (1999)

The protagonist of the game, a high-school student, finds himself and other characters (mostly female high school students) trapped in a marine research facility. Exploring the abandoned building, the hero discovers the research staff died under mysterious circumstances. Was this a murder committed by a human being, or some sort of an unknown evil force? The hero does not have much time to think, since whatever took the lives of the scientists also threatens to murder them...