Square Enix has trademarked "Parasite Eve" in Europe (via Gematsu), which has led to all kinds of speculation as to what such a move can mean?
Square Enix is currently in the process of remaking Final Fantasy VII in what may be the most highly anticipated video game that is currently in development, but there may be other gems in their library that are also being revived.
The most obvious guess is that a fourth game in the Parasite Eve series is in development. One hint at this can be seen in the initial trailer for the Final Fantasy VII Remake, where a banner featuring Aya Brea (the star of the Parasite Eve games) can be seen hanging from a building in the city of Midgar. This may have been a subtle hint that a new Parasite Eve game was in the pipeline.
The last game in the Parasite Eve series was The 3rd Birthday, which had some interesting mechanics that were hamstrung by the technical limitations of the PlayStation Portable. The 3rd Birthday received a mixed reception upon release and many felt that this reaction spelled the end for the series.
There is also the strong possibility that the first Parasite Eve is being remade in the same manner as the Final Fantasy VII Remake. Parasite Eve was released on the original PlayStation and its graphics have aged terribly, so a modern visual overhaul would definitely benefit the game.
It's also possible that the first two Parasite Eve games are being remastered in the same way that Final Fantasy VII and Final Fantasy IX were, with the graphics cleaned up and a few quality of life improvements added to make the game easier for modern audiences.
There is also the distant possibility that the original Parasite Eve is finally being released on the PlayStation Network in Europe, as the game was never actually released in Europe, even though Parasite Eve II was.
Whatever the case, it's exciting to think that we may be receiving more Parasite Eve content after so many years of the series being abandoned. The original Parasite Eve was one of the best games on the PlayStation and a revival is long overdue.