I can definitely appreciate the humour in those Starcraft references. Everything here is very functional and supports the main mechanic of clicking to restore power so I would have to disagree with the criticism from others that generators shouldn't need to be clicked on, it would turn the game into a typical incremental game and you would lose what makes your game unique. However, I agree that as you get further in, it feels less and less rewarding to be recharging individual towers.
Given the limited space to place towers and the limitations of the towers themselves it's impossible to go any further than a certain point. As the difficulty of the waves gradually increase it gets to a point where even if you play perfectly you will still lose so I think being able to upgrade towers' damage/range/chargeAmount could extend that playtime for quite a bit longer. There is also a small gripe with the AI, I could be wrong but when 2 towers attack the same object it appears to do 1 damage in total so either adjust the AI to only have 1 attack an object at a time or make sure the damage stacks up properly.
Finally, something that's letting this down is the lack audio which can make the game feel a lot more satisfying and responsive to the player's actions. The Audio category has been left available to judge so for future reference keep in mind what categories you want to be judged on and opt out of categories that aren't present in your game.