Gantz

This i happen to come across by accident and thankfully i did!

Gantz on my list ranks pretty high. It's a completely unique story and idea. Admittedly the 1st episode may put most people off but you must persevere!

Selected people when they die end up killing aliens for Gantz ( a giant sphere of a thing, nobody quite knows what! ). Kay Kurono and Masaru Kato, two high school students die in an unfortunate accident and are sent to Gantz for "processing" along with many other people.

The aliens are the most creepy things i have yet to come across in Anime. It's basically a game of survival. Until you reach 100 points you will have to keep on killing, harder and harder things.

More here.

Gantz is captivating and addictive. From what i've read so far of the Manga it could of been stretched a bit, plus the Manga is a bit different. Still good though!

They made two films for this Anime, never quite pulling it off.. Then again who can make an epic Anime into a real life action film??

Also, the music is creepy and just fits perfectly! Prepare for one hell of a ride! :)