i beat the game 3x and picked up every new upgrade type i found, but have not unlocked this achievement (also what does the pb upgrade do)

Hi! I'm trying to get variety pack achievement, but the rat upgrade is super hard to get. Using Weapon 3 Machine gun, went endless, and went through 100+ upgrades to try to get it but to no avail. I don't know if I'm that unlucky but I should think I should be at least getting it right now. Is the upgrade bugged or is the rng for it so low that it is really hard to get? If it is that then please higher the chance for it to appear. Thanks! https://imgur.com/a/kany46W...

Is there an endless mode or would it be possible to add one? Seems like it would be fun to see how many upgrades and rats one could get. Perhaps just endlessly increase enemy number and health?

Great, life changing game! However I'm not getting any achievements. Just wondering if anyone else has this issue or if it's new :)

yes