So I'm going to preface this by saying that this suggestion would take a lot of effort to implement, but I'm going to suggest it nonetheless. This content would be a huge boost for the server, as Zenyte would be the only OSRS private server to have it as re-playable content.
In addition to our current selection of modes (regular, ironman, HC iron, etc), I suggest that Zenyte offer Twisted and Trailblazer modes. These modes would be linked to your main account, so the rewards would be redeemable on your main. At the start of the league, you would type in the name of your main account so all of your point rewards will register with that account only. Only one league account can be linked to each main account to prevent players accruing easy points with alts. Each league would only last for 2 months and would repeat in cycles. At the end of the league's 2 month duration, all the points earned from that league will transfer to your main account, and you can purchase rewards from a league-specific NPC at home. League accounts will be deleted after the league period ends, but your previous progress will be tracked on your main account's Game Noticeboard.
The leagues would include all the content available in leagues, including all of their respective limitations and buffs.
There would also be a league hiscores for points earned as well as for levels. The top 10 players in each league would receive Zenyte store credit / OSRS gp / other prizes.
Twisted League Rewards:
Twisted League Trophies
Twisted Teleport Scroll
Twisted Blueprints (redeemable when construction releases)
Trailblazer League Rewards:
Trailblazer League Trophies
Trailblazer Graceful Set Ornament Kit
Trailblazer Relic Hunter Outfit
Trailblazer Rug (available with construction)
Trailblazer Dragon Skilling Tools Ornament Kit
Trailblazer Player Owned House Globe Statue (available with construction)
Trailblazer Themed Banner
Trailblazer Home Teleport Animation
Player Owned House League Room (available with construction)