Thanks a lot for playing the game and glad you liked it!
No there is no end and damn thanks a lot for going up to 19 :D. The difficulty was originally meant to be has you described harder and harder but it was making the early game too hard or too easy. So we scarified end game to make sure everyone could do a couple of rounds with some challenges an end would have been a good way around. But yeah scaling difficulty would be the first thing to improve in the future.