This game's graphics, animations, sounds, music, etc are all great. However the gameplay as others have said is quite lacking, not bad by any stretch, but there's really no incentive to do anything besides standing around a certain area and mashing the attack button.
I think giving the player more attack options with usage limits on each would be better, For example you could have a sword attack that can be only used to much before needing to recharge, same with a ranged attack. You should also include more enemies that can only be attacked with certain attacks, such as a flying enemy that can only be attacked with a ranged attack and an enemy that can only be attacked with melee attacks, this would make the player be more mindful of what attacks they should use and be careful not to deplete one of them.
Another problem is that there is no reason to protect the generators, I think to mitigate this, the player should get stat buffs or extra abilities for killing monsters targeting them. Each generator should give a different buff, making the player want to protect them all in order to have the greatest variety of buffs.
I also think there should be rounds. Each round should have a certain enemy requirement that is visible to the player, and at the end of the round a boss appears. If you did a good job protecting the generators in the round, you'll do better against the boss since you'll have access to the buffs.
Sorry for the long review, but I see a lot of potential in this game!