which arc/ chapter are you on?
you really need to catch up with it, though u could take your time cos it comes out every 2 weeks, but its alway a mystery and gives food for thought every chapter it reveals.

very exciting how it turns out as anyone can die, even the main characters, not like how dbz, bleach, naturo, one piece where they will be injured very badly but will alway survive to fight again.

not to mention this current arc in gantz has surpassed nuri now, and that was a near impossible alien to kill, since all the 'pros' were massacred and are way stronger than the main characters.

Gantz isnt like DBZ, its like real life, no matter how strong u are, u can die from making a simple mistake and that even 'pros' can die. having the most experience only means you have a better survival rate, there is no guarantee in winning.
its like being in a war, even the best soldiercan die from a few bullets from other soldiers, its just he will have a better survival rate.