It definitely needs a lot of balancing work, and ideally a better end state than entropic invaders for sure, that was just the easiest one we could make in time provided to make sure people weren't playing the game for an hour per run. The higher your Zeal the easier it is to deal with those Invaders without taking any losses but also the less likely you are to add more followers, we could probably communicate its effects better to the player, but mathematically it does matter. Also the higher you keep your Karma the less likely you are to get a bunch of invaders dropped on you at once so if you're not paying attention to either of those numbers you're likely to feel blindsided by the consequences, which again is part failure on our end to effectively communicate the exact consequences beyond the intro and help text.
Not sure what you felt was surviving a "long time" without any Score reference, but just to share some reference in testing the highest dev score was 856, and post submission the highest score I've seen was 1200.
Thanks for taking time to play and leave some feedback. We appreciate it!