I know. I just used it as a conversation segue.
That is Fate/Zero, which is a light novel/amazing anime. Hollow is the sequel.
Realta Nua is an updated release, first for the PS2, then for the Vita. The Vita version contains new openings for each route done by Ufotable (The studio that did the anime adaptation of Fate/Zero. You can watch all three here, although they are low quality because it's impossible to extract the video files from the Vita, so they are filmed with cameras.)
It removed all the H-scenes and replaced them with kid-friendly alternatives, and updated character models and soundtrack. There is a fan-made Realta Nua patch on the internet that I recommend getting.
They made a fighting game based on Fate called "Fate/Unlimited Codes."