Well, a friend and I surpassed the "undefeatable"wave; wave 59 and got to wave 60! Only then, were we shocked on what surprises wave 60+ held... It was Hell but our strategy had dominated and... still is dominating(2:04 AM right now and at Wave 117)
This is how our units were placed a bit after Wave 60.

And this, you ask? This is what Wave 60 and Beyond look like.
HELL... without the fiery pits of lava of course :)
Notice how much Gold we have... - Wave 117, Yes, we did upgrade. I think Maydrian1 got up to Level 19 for Melee and I on the other hand decided to go afk since I knew we were just going to defeat the numerous amount of enemies that came towards us.
I know the image says wave 113, but when I looked back, we were at wave 117... I looked back again and we're at Wave 128 :3

Just wanting to show off ;D I guess.