Yesterday I was playing the first Endless Assault level. And a funny thing happened.
Apparently I found the perfect solution somehow, since I did not die for more than 2 hours. Strategy Points damages with a percentage of the enemy units, so they scale well. What made my defenses impenetrable was Pride points though. Coincidentally, a Pride point in the right place killed over 4000 units, and its damage was more than 100 million. And since it is the only tower with such a damage, it continued to be the main damage dealer, killing more, earning more damage. This caused a deadlock.
For more than 110 minutes of my playthrough, I had all towers at maximum, placed my cursor in a corner and went to go wash dishes and walk around the house etc. I think the game would continue until eternity, if I did not get bored and sell the towers to intentionally lose the game.