Sorry for my bad English

My review is separated to 2 parts , first contains my review for general plot , and the second my review for the end , so If you haven't read the manga yet , I recommend to take a look first .

Basically this anime is like Kaiji ( survival and psychological ) , No game no life ( game / puzzle ) , btoom ( survival ) in my opinion .
In general , the main character and his friends have an ordinary life , but one day they were transferred to an unknown world , but after that they were involved in a game , and after that the secret of this world is revealed , basically if you want to continue residence you need to recharge your visa ( of this word ) by playing games by putting your life in danger , otherwise when your time limit reaches ( visa ends ) you receive your end by a laser from the sky penetrate your head .
What I have liked the most , is the psychological stress is all games , especially the heart one ( psychological game ) , the kill between the players to survive .
Every game , make you feel that the mangaka is genius game player .
The art was perfect , some scenery were unforgettable , there were also a frames like 3d

**************** Spoilers for the ending of story **********************
after reading the end , I was pretty disappointed .
For me , I think that there still nothing clear for the reason why there were transferred to the borderlands , And making all things like there were just dreams make it more and more bad , and also if the meteors were the reason of the transfer , does the borderlands repeat July month as it was said , and how the players gonna continue to transfer to the borderlands without meteors ( if that the real reason ) .
So for me I think it is a big mistake to end the story without revealing all things , I believe it is one of the mangaka duties to explain all mysterious things to the reader