Due to the nature of how HnH works, i.e. every year or 2 it resets worlds, it actually plays much more like a MOBA match than it does comparing to a theme-park or grind or sandbox MMORPG.
Everyone starts with a new char at lvl1, the playing field is somewhat even between players until at some point one side gets an advantage and snowballs with it into infinity, dominating all opposition with it until the match ends. From a progress perspective (Quality/Tech, pvp odds and player progress), playing Hafen is like playing a 1-year long League of Legends match.
What I'm saying is, it would befit HnH to have a system that lets players experience a progress in their accounts that is beyond the game world and actually persistent across worlds, unlike the mere footmarks they leave in a single world right now.
Achievements or medals would be an example. A tribute to the accomplishments of players in each world. The medals could be world-specific, e.g. "killed 90 trolls" w12 medal, then a "killed 90 trolls" w13 medal etc. Or they could accumulate over worlds, so "killed 90 trolls" for troll killer medal 3, then "killed 160 trolls" for troll killer medal 4. The former is how LoL does it, the latter I've seen in another game. I like the latter more personally because each medal progresses potentially infinitely, just like most things in HnH do.
An account level would be another. An attest to the loyalty and veterans of the game.
The icing on the cake would be earnable points that can be spent on some trivial nonsense in each following world. Like random pleb hats from a pleb lootbox unlike the non-pleb hats from spending. Then the levels could be gaining its worth from it too, by earning the player points for each levelup.
I feel like this is THE thing that HnH is missing. It's not like Salem where the world always stays and players have a reason to continuously play.
But if it had some ways in which players can progress even after a world ends, players would still continue for their account's sake for the next worlds even if they die or mess up in one world and even if the world is nearing its potential end at the end of each year, there would always be a reason to continue playing because they could still level up their account and earn medals.