Leave it to Japanese titling conventions to confuse. I know Steins;Gate as the anime with the weird semicolon that a lot of people say sucks for the first few hours of episodes and then suddenly start talking about how great it is. It's like Final Fantasy XIII, I guess.
Apparently, it was a visual novel before an anime, and part of a series that includes other visual novels with semi-colons in the title, the next of which is Chaos;Child, which is set to release in Japan in 2014 and has a more direct tie to predecessor Chaos;Head.
The more you know!