It was about this large group of kids, like, from the same class, on some vacation, and on the beach they end up finding this cave with this creepy older guy in it, who asks them to play a game, and it goes all scifi technology and they enter into some game system.
And it's really about fighting some...robots, or aliens, or something that are attacking, but they all collectively control the one giant robot thing they're battling with, and they all have these special seats that remind them of special things from their past or something...in the giant robot control room.
and they never see the guy again. and one of the kids dies in the first episode.
That could describe quite a bit of things...but I've never watched mecha, so I dont really have any clue what that could be...
Thanks everyone.