Are you going to add more Campaign levels?

Titan Brawl was created as a PvP game. The Campaign mode was added, so the new players can get used to the mechanics. At the moment we are not planning on adding more levels.

How can I change my Avatar / How do I unlock the Achievements?

You can change the Avatar by editing your profile. You can chose one of the Game avatars or your Facebook profile picture.

To unlock the Avatars you need to complete the Achievements (you can find the full list in the Menu).