Here's how much I know about this game: I made it fairly far & started running into archons & those giant mecs that lay down the aoe as well as their normal support guys (shield bearers, lancers, etc)...& dying. Over & over dying like a champ. It wasn't too bad when it was just archons. Still super hard but I could usually pull it off.
Last night I realized I could upgrade the gts. Seriously. I've got a maxed out ranger & 2 almost maxed grenadiers & I JUST NOW figured out I could be running 6 members. /facepalm.
So now the game is fairly easy again & I'm completely sure that I have no idea what I'm doing & probably missed something :)