I think there is something in all of that, but yeah not in the current state of the game. Like skeletons just doesn't spawn often enough to survive longer than 16 seconds.
I also can't help to think that if you reverse the mechanics it may actually improve the game. Like if the game was score-based and as you kill skeletons they start spawning CLOSER to you and more often. And if they reach you - arena becomes bigger and skeletons are harder to hit. Like change punish for giving rewards and opportunity to show your skills even more.
Anyway, good job guys!