I suggest put some more deeper shadow on the chain in order to create volume and also apply some rough texture to the chain, similar to the texture on those letters and phrases. Then use glow effects around the chains in dark red.
The empty space seems to bothers me somehow; try put the deathnote there, make sure it kind of blend to the background or fade into it like into abyss. With this element there, it might help convey the theme and also showing L looking at the note book or suspecting it. Anyway try it out and see if you like it.

Hey, I like the color palette and the concept I think you are trying to reach, I do know nothing about Death Note besides what a friend have told me about it. I think you are trying to do a not so FX wallpaper but still not so minimalistic,
what I could suggest you about it is..

first: do an effort to vectorized the image or get a cleaner resolution of it (the texture and filter you are using to hide the fact it's a amplification may not be working)

second: the big black center area make it look quite incomplete or like something is missing, I could suggest you to move a downwards the chain & title, trying to put the nearest to L you can, maybe the upper part of the title could look better with bigger typography, hehehe

sorry if I went on writing a long comment, but I see a great oportunity for your wall =)!