I am part of a (very small) team that has recently started working on turning the Warmode concept (a link for the unenlightened: https://terrariafanideas.fandom.com/wiki/War_Mode ) into a reality. I made this post both in an attempt to recruit new members, and to show you what has been done in the mod so far.
Dev Blog - Game Flow
In order to create a mod that adds a whole new mode to Terraria, it is important to look at how Terraria's previous modes were formatted, so that Warmode can follow suit and feel like it belongs in the base game.
Here is a flowchart demonstrating the gameplay loop of Pre-Hardmode. While this flowchart is not all-encompassing, there are some important things to consider here. The main aspect in the explore -> boss -> explore cycle Terraria implements. This can be seen how the game soft locks bosses/biomes until the previous one is beaten (excluding the dungeon), such as how without demonite/crimtane armor you probably can't survive the jungle, and how to get those you need to be able to beat the Eater of Worlds/Brain of Cthulhu. This can be seen yet again in Hardmode, although there are more events in order to compensate for the lack of many new biomes to explore.
(Confection and Wall of Steel are parts of the Warmode Mod) An important challenge of designing Warmode is how to replicate this exploration experience provided in Pre-Hardmode and Hardmode when there are no new biomes to explore, and you know the world top to bottom.
Here is the current Warmode progression flowchart. As you can see, it is nowhere near complete, but there are some things that are being done to give the player a fresh exploration experience. We kept the at least one new biome approach of Hardmode, and are also having a major change happen to a preexisting biome (the specifics of the change TBD). On top of this, some new events are being included, some of which will have major impacts on your world (no spoilers), all in tandem with the new Warmode mechanic of having to choose a biome to fight for, which causes enemies in said biome to be passive, but enemies in other biomes to be extra hostile (more on that in a future dev diary). Warmode is still in its early stages, but I believe one day it will be something great!
How do I join this mod?
Simple, join our Discord and talk to me (my username is mithrilsword1) about joining our mod team. Just because Warmode is a preexisting concept doesn't mean that you idea wouldn't be included (in fact, as long as it isn't too ridiculous I'm almost certain it would become part of this mod). We especially need coders and spriters. I look forward to having you as part of our team!