Long War team was contacted by 2K mid 2015 and have given feedback on the mod tools and where the game could be made more moddable as they have used the new builds they have gotten from Firaxis.
The modding tools looked amazing. There's easy access to everything you could want to fiddle with.
They have mod templates (Map packs, voice packs and so on) that you can select to get started with that kind of mod.
Debug mode (dev console) has alotof options, line of sight, fog of war, destroy tiles and much more.
Replay mode for tracking down bugs, every save file makes a replay.
SDK Assets
* 1900+ XCOM2 gameplay script files
* 2400+ Maps (cinematic, environments, menu, geoscape and more)
* 7000+ Environment props
* 4000+ Materials
* 10000+ Textures
* 2000+ Sounds
* 3000+ Particle systems
* 600+ Character assets
* 600+ Animation sets
Lots of other stuff. It looks fantastic from a modding perspective.
Edit: And someone will make a gun that shoots pigeons on day 1.