@PGDave I see conflicting reports from players about the difficulty of invader vs. xp given. To help these players how feasible would it be to add a selection (perhaps in settings) to allow for 2 or 3 difficulty settings? For example:
Hard setting is all level 50s payout of 300k xp
Medium is all level 40s payout of 200k xp
Easy setting is level 40s with a payout of 125k xp
Of course tower balance is the most important thing right now.