Not to sound like a cliche, but ask yourself if Jesus were with you (and He always is *S*), would you do watch it, or play it, etc.?! I've clean up many things in my life trying to live by this simple rule, and I haven't regretted a single thing. Things I thought I would miss, I haven't. When you know your doing your best to please Jesus, it's all worth it.
I think the other thing to keep in mind when considering whether or not Jesus would want you doing it is whether or not that thing is affecting your relationship with Him. Outside factors can influence the question of, "Would Jesus want to see me doing this?" For example, if you have a family member who is anti-Japanese, then you may grow up thinking all things Japanese (anime, for instance) are bad, and therefore you would think that Jesus wouldn't want you watching anime; however, that decision is based upon hearing someone tell you that Japan is evil your whole life, not necessarily upon any teaching of Jesus. If we consider whether the thing in question is affecting our relationship with Him or not, then we can get a much clearer idea of where it actually stands with Jesus. Let me give you a personal example:
As I've already stated, the items in question here do not affect me in any negative way. They are entertainment, although Rawshik has given me good reason to strongly think about the horror subject. On the other hand, my taste in comedy did have adverse effects on me. In short, I listened to vulgar comedy (Dane Cook, and comedy bands like Steel Panther), which ultimately influenced me to tell vulgar jokes. We know that Jesus doesn't like vulgarity, so this was obviously affecting my relationship with Him through my behavior. Jesus taught us that our behavior is important, and since mine was out of sync with what He would have wanted, I had to change it. Now that I've found Christian comedians (such as Bob Smiley) and stopped listening to the vulgar comedy, I can work on cleaning up my humor and getting it in line with something Christ appropriate.
Now, with the other items, I do think that some selection is still in order. For example, I like anime, and that doesn't affect my relationship with Jesus; however, that doesn't mean that I shouldn't avoid some anime. Earlier this evening I was watching a show called 'Tari Tari', which is basically about a group of high school friends who start a choir. It is basically a cute, slice-of-life show with no bad elements, so I don't see it bothering Jesus. On the other hand, there is an anime called Mnemosyne, which, as I understand it, has a giant lesbian orgy in one episode. Obviously this would not be something that Jesus would want me to watch, since pornographic material is bad. In other words, while anime in general does not affect my relationship with Jesus, there are still titles that should be avoided.
I actually had a meeting with my pastor this evening, and the subject of fantasy and all that came up. He seemed to agree with the general sentiment of this thread (we didn't talk horror movies, though), and he did say something to the effect of our hobbies allowing us to reach other people with the Gospel. That makes a lot of sense to me. After all, if you generalize an entire genre (anime, fantasy, sci-fi, etc.) as evil, then how do you reach out and find common ground with people who aren't saved and who like that kind of stuff? Most people aren't going to take kindly to you just shoving the Gospel in their face while telling them their hobbies are bad. More than likely, they'll be more willing to listen to someone who shares their hobbies.
I think when it comes down to it, we should ask ourselves, "Does this particular thing affect my relationship with Jesus?" in regards to the broad spectrum of things (video games, movies, books, and so on). If the answer is no, then I think we need to start looking at individual items within that category and say, "Would Jesus like to see me reading this book/watching this movie/etc.?"
Well, anyway, those are my thoughts. Off to bed for me now!
