 If you liked
Gantz
|
 ...then you might like
Tenkuu Shinpan
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Both are about people trapped in another world, set up by some mysterious person, with situations that put their lives at risk, enemies and deaths. Tenkuu Shinpan has more shonen style and paranormal powers and gantz has futuristic weapons
If you liked one of them you'll probably enjoy the other.
Enjoy the reading