How to make new unit actions?

[AIEND]

I want to add two kinds of siege attacks to the unit, one is to throw torches to set fire, and the other is to use a sledgehammer to smash the wall. How to make related actions?

[ChronA]

1. Create new variant XML files for each new animation in ...\art\variants\biped and ...\art\variants\quadraped for infantry and cavalry respectively.
   • The actual animation sequences should be copied from existing sword swinging and sling throwing variants. That will save you from needing to make any new animations with Blender.
   • You might need to create a few extra variants for each action to accommodate units with differ sized shields.
2. Add the proper new <variant> tags for each new action to ALL the actor XML file... FOR EVERY SINGLE UNIT IN THE GAME!!! 
3. Add code to the Component files (...\simulation\components) for UnitAI.js, Attack.js, (plus all the other combat components that interact with them) to allow units to know when and how to use their new attacks, and what to do when hit by them.
4. Add new attributes to the unit-template XML files to set the speed and damage for the new attacks according to the syntax you set up in the Component files.

I'm probably forgetting something, but that's what I remember from last time I looked at doing something similar.

Needless to say it is a tremendous amount of work, and unless you are actually a god-tier coder you should recruit help if you are dedicated to seeing this idea realized. Don't try to do it all on your own. It will take ages, and there is a good chance the next update could wreck all of your work before you even release it. Work smart by communicating with the main devs, sharing the burden with collaborators, using version control software for everything, and pacing yourself. This will protect your work and mental health in the long run. 

Other than Hyrule Conquest and maybe that one Pony mod, I don't think anyone else has ever attempted a renovation of this scale in the last 10 years. But it can be done if you are smart, persuasive, and committed to seeing your vision through. Good luck and best wishes!