As of this review, I have recently finished the spin off manga to the somewhat popular titled Gantz.

We are really only introduced to two aliens: first ones kinda basic, similar to a few aliens being fought in the original series. Second one, which is the finale, was quite impressive in my opinion. In terms of gore, there was much more less, but there was enough to satisfy me. If you want to suck in all the lore and details about the world or universe of Gantz, this one will shed some more down. Another thing worth mentioning is this story goes more towards fighting against the aliens. There is a relationship but drama seems to lack more than in the original manga, however we do get to see the characters relationships change throughout the story. Sadly, some thing in the manga do seem to go by a little fast due to it's short length at time.

If you read Gantz and enjoyed it, id give this one a quick read.