Idea:
The castles gamemode is basically bridges with a twist.
More information:
There should be a barrier (like the one in skywars) for a minute or so.
You need to capture 10 points.
There should also be an npc where you can buy stuff with iron or gold.
Also, there should be generators.(This should be quite easy to implement because they can use the treasure wars infrastructure)
I also think that there should be a bridge made out of campfires and every 3 minutes they will ignite for a few seconds then go out.