I definitely can't call my little creation better than Into the Breach, but it is heavily inspired by that game. The day limit serves the purpose of being an ending point. I've brought this up as a point of discussion on my SubscribeStar account, and many were in favor of using a limited-time format. It will make more sense after the Sprout Queen is added to the game, since she will present an optional challenge to try to complete within the time limit.