So, every time we go to a new map, the arena map becomes harder and harder. Yes, you can repeat arena fight as much times as you want, but it is really hard to go play big maps against other players for newbies. (I really never played quickmatches that are not on small earth, because it requires lots of time and reward is the same) Now I was struggling on Ursa arena and won it by accidentally finding and killing opponent's general. If not for that, his 40 power army would conquer all my territory and I would lose again. Some players are so good, you don't stand a chance to win in any battle against them. Why should arena become such a hard thing in idle game? Without winning a battle in arena you will have to waste lot of time to gain those resources it provides, though, it should be viable to all players, both veterans and newbies!
The QM (QuickMatch) system tries to match you to an opponent with a similar rating on the template you are being matched on.
If you win a few games, your rating will go up, so you will have to fight players with more skill. If you lose your rating goes down and you get less skillful players next game.
WZ is so much more than Idle, you should play regular WZ as well, not just the Arena games.
