2.2 is here, which should add some more complexity and challenge to settlement management. You won't be able to endlessly grow settlements any more. The happiness of your citizens and the administration capacity of your rulers will slow you down, forcing expansion and trade. The goal is for advanced settlements to feel somewhat like an optimization puzzle, trying to eek out the most performance of the limited Administration and resources at your disposal.

New Features

• New world generator, producing larger worlds, and larger regions.
• Small amounts of copper and limestone can be found in mountain ranges.
• New class of settlement resource, Infrastructure. Infrastructure can't be stockpiled or traded, as it represents the abstract support structure of a settlement. Food and Housing have been converted to be infrastructure.
• Administration limits. Settlement growth is now capped by Administration, which you get by upgrading your admin center. This will add element of an optimization puzzle to advanced settlements.
• Tooltips on some icon displays and combat stances.
• Economy reworked to be based around per-season item production and consumption.
• Morale. Your citizens now have morale needs, which you can address through providing happiness with several new types of structure.
• Riots. Unhappy citizens can now take to the streets and riot. This is handled through a chain of events, with some interaction options. You can throw feats to placate your people, or even execute the dissenters.
• The pick structure dialog now groups structures into a hierarchy, reducing clutter.
• Bridges
• If you don't have enough housing, homeless citizens may leave your settlement.
• In-game encyclopedia, with unit stats, game mechanics, and a getting started guide.

I went into more detail on how the new mechanics work in  the 2.1.1 and Morale Update Preview devlog.

Migrating Old Saves

Like most releases, your old worlds can be loaded in 2.2. However, I don't recommend it this time. There are changes to the world generator to produce worlds more compatible with the new mechanics in 2.2, and old settlements will likely die a quick death from riots and insufficient Administration.

Experimental Features

I'm trying something new with experimental features. In part to find problems with the mod API, and to experiment with some ideas, I'm going to be adding more built-in mods. These mods are distributed with Bronze Age, but aren't enabled by default. You can opt-in to them by enabling them from the Mods menu.

The first one is respawning Masklings, and comes with 2.2. Every year a trigger will check the world, and place new settlements for Maskling tribes that have been cleared out.  It has the potential to flood the world with Masklings, but that sort of challenge may be right up your alley.

Mod Changes

The existing scripts have been more thoroughly documented, and the riots and homeless triggers demonstrate some more advanced abilities. t_riots, for example, creates new tribes and units.

There's been quite a few changes to the data file layout, which I've covered in a Mod Upgrade Guide, for upgrading 2.1 mods to 2.2