Seriously though, name a single D&D campaign .. EVER .. where you level up from 1 through 20 in a single story arc.
I thought you guys wanted authentic D&D?
One to 20 IDK BUT.
Most Dark Sun adventures recommend starting at lv 3 because lv 1 PC's has ZERO chance of surviving outside of cities
Descend to Arvenus is a lv 1 to 13 adventure. And if there is a continuation, it would be probably lv 14-18 or even 20.