So - just a little update to say thanks for all your feedback!
Update 001 Notes:
#1 - Added new ‘Rush’ option with 9 new 'small' levels for quicker games
#2 - Added energy-award on enemy-destroyed for gameplay balance
#3 - Changed large-walls to match small-walls for easier differentiation
#4 - Made ‘Skirmish’ level-generator quicker to unlock for improved access
(see Main Menu for new 'Rush' levels)