I was about to look for anime like Guilty Crown then I came across an interesting anime called Steins;Gate (it's nothing like GC).
This is definitely a sci-fi anime. It's pretty damn hard to understand with all the science shit flying out of their mouths, but I was able to comprehend what they were saying despite my young age. From what I can understand, it's about time travel.
It had a really slow beginning and took 3-4 episodes just to set it up, but trust me, it's worth it. After you get past all that, things really start to get interestingly intense.
I'm only on episode 14 but I'm gonna marathon through it tonight. So far, this anime is great. It can even get a little dramatic. The constant role playing of the main character is a bit weird tho.