Why can't we grind beyond level 20 in Fallout 3?
I'm asking because it's becoming increasingly difficult to deal with Death claws and I really want to experiment on various other perks. Does it have something to do with the story?
Solution 1:
20 is the forced cap on levelling for Fallout 3.
It can be expanded to level 30 by purchasing the Broken Steel DLC.
As for dealing with Deathclaws,
get crafting the Dart Gun and immobilise them from afar.