One anime on that poll which a lot of brehs in this thread are sleeping on is Bokurano. Of the 10 on the list, it should be #1 easy. No other anime have I seen have I thought "wow these poor kids
" like that.
For a description of it:
A group of kids/teens go in a forest, find a secret hideout and get convinced to sign up for a game by a stranger. After that, he tells them details will come later. A couple days after, while they are hanging out, a giant alien like machine is attacking their city. They all get teleported into a mech and one of them is told to fight the enemy. He wins then falls off the mech & dies and the rest are transported away.
At first they think that one of them pushed him off the mech until another battle happens and same result. They learned the energy needed to power the mech is their life force so that piloting the mech basically equals death for the pilot win or lose, and that if they don't pilot the mech and win within a time limit, their whole planet is destroyed. They need to win a certain amount of rounds (there's less rounds than people in their group so someone is "safe" but no one knows who and the order is decided to amp the fukkery).
The other machines are later found to have groups from other planets similar to theirs in it, defending their own planet from destruction. The mech battles goal is to destroy the part where the other people are in, effectively killing them.
The main characters are all incredibly shook, and they are all in panic mode. Some of them break down mentally, etc. The government is also paying attention to this along with the media (the fights are clearly visible to everyone) and they get involved.
Best part about the anime is the characters. They have a certain realness to them. I consider a rewatch but them I'm like