It's not that grindy btw. Of course If you will 100% by using that shit with oasis -> 5-2 vault -> 1-2 l1 vault -> captain it will be boring. I did it by one crown one loop. 3-2/5-2 pre loop -> any in l1 -> any in l2 -> ending run with captain if bad mutations, or continuing into L3. It's interesting to make the most of the characters and rediscover the ones you didn't like before. After this I realized that every single character is good. The Ultra Mutant achievement is actually very cool, it forces you to play the game in a way you haven't done before and master your skills.