Nearly all of the data in Airships: Conquer the Skies can be modded, and modders have created some excellent additions to the game. I want to encourage you to try modding too, so here is a detailed guide.
If you have any questions about modding, it's worth joining the Discord, where you can find helpful, seasoned modders. You can also contact me directly with any questions. If you get stuck, you can even send me the mod you're working on and ask me to help you.
To learn how to mod, you can read this guide, watch this video, or if you just need a starting point and are happy to explore on your own, here's the very very short version:
The heroes introduced in the Heroes & Villains DLC can be modded, changing them or adding new ones.
You can download a simple example mod here, for you to study and modify. You can also look at the already existing heroes in data/crossplay/heroes/HeroType. You can probably figure things out just from that.
The rest of this post attempts to document everything exhaustively
Special eras are one of the features that I introduced in the co-op and conquest update in August. These work by temporarily changing the rules of the game, and may also have a victory condition, where an empire can be rewarded for ending the era early.
Like pretty much everything in the game, these are data-driven, so you can add new ones by modding. Here's how.
Here's a quick tutorial on how to mod a new city upgrade into Airships - a Workhouse, which increases city industry but also raises unrest.
An in-depth guide to how modding works in Airships, and how to create a mod that adds a new module.
This is an in-depth tutorial for newcomers to modding. We are going to make a simple mod that adds a new kind of enemy to spawn in strategic mode, a peasant uprising. You need no graphical skills for this one.
Bonuses are a system in Airships used to give players access to new modules, armours and constructions, and change their stats. You can use them to add new technologies, heraldic charges, and monster nest rewards.
To get this out of the way from the start: the crew animation system in Airships is a bit weird. If you don't need to create new crew, skip this one. But I'm going to do my best in this article to show you how it works.