This is an Idea I made for something more different but I think it can fit well into current Curse Craft.

A contract system much like the Star Plasma arc where players will get a contract to either protect or kill randomly selected player. Contracts cannot be made on players with a grade below Grade 2.
After a period of time if that player is not dead or is dead, the players who completed the contract will gain the contract rewards. If the contracted player DCs during this period of time the contracts will become void and a vote will begin. If the vote is passed by a majority of the players in the server the contract will be reinstated on another random player. If this happens a 2nd time no vote will be given to the players and the Star Plasma contract will be put on a cooldown. Contracts can only be given if the server has a minimum player count. If count is high enough multiple contract targets can be made.
Players can only be apart of the Star Plasma contract system if they are in a certain realm (Heian, Shinjuku, Badlands, etc.)

Heian can feel kinda empty at times as you travel from point to point and while you could add curse spawns to help make it feel more alive, I don't think that will remedy the issue, as most of the time people will just run past the curses and ignore them on their way to a seal or extraction. However If a high grade curse is spawned to protect a seal, then I think that issue will be mostly solved, as even if there are no players to contest the seal, then there is still an element of action. Bonus if there are players as it would add another layer of difficulty to taking one.

While out of combat background music plays, this could change depending on where you are and what realm you are in. Once combat tagged the music turns from idle to intensive but this could obviously be done using a gradient where it ramps up in intensity depending on how long you have been fighting for. Once a domain is used the theme song related to the tech could play (this could be overwritten with custom domain soundtracks)This music could also change depending on what tech initiated combat with you or change depending on a specific curse/mob you are fighting with priorities for songs being given to avoid stacking music if you fight multiple named mobs.

If its requested enough it could also have a toggle to turn this feature off if its too loud, overwhelming, or you just don't wanna listen to it.