Steins;Gate, erryday, all day.
It doesn't have an official English translation yet, but there's a fan-patch that's pretty darn good anyway if you can get your hands on the Japanese version. It's a modern-day science-fiction story set in Japan about time travel. On PC (well, primarily; It's on many consoles as well, but I don't know how resourceful your importing skills would be and being a VN it'll practically run on a toaster). EDIT: To clarify a little though, there is an announced English version based off of the fan-translation slated for an early 2014 PC release. I hope it keeps the Japanese voice acting though, it'd just feel weird with English voice actors (not unlike the anime).
The BlazBlue series is also pretty fun, if you also like fighting games. Probably one of the few fighting games I'd recommend solely based on its story, as it lampoons and parodies many stereotypical anime tropes and has some pretty hilarious writing mixed in with the more heavy or ridiculous stuff. Also on multiple systems, primary being Playstation 3 I believe. The first game is on PC, both are on the Xbox 360/PS3/PS Vita/... other things. You don't really need the first game though, the second summarizes it fairly succinctly. Also, as per typical for console fighting games with multiple re-releases that are slightly tweaked, if you do get the second game, Continuum Shift, make sure you get the EXTEND edition.
And if you're a fan of puzzle games, there's 999: Nine Hours, Nine Persons, Nine Doors and its series sequel Zero Escape: Virtue's Last Reward. The first is on the DS, and the second is on the 3DS and Vita.
All of them are ostensibly T-rated, by the way.