How to keep population happy

From Meedoc, one of the game designers:

The anomaly reinforces the FIDS brought by the tile when exploited. To benefit from the bonus, you need to exploit it by building the city next (or above) to it, or expand and try to reach it by building a borough.

• By default, you'll heal a very slow 5% per turn.
• Standing on a friendly city boosts this to 10% (garrisoning has the same effect; it doesn't stack).
• Watchtowers give you 20%, and this rises as you improve them to Lookout Towers and Remotuscope Factories

This may not be enough, though, so you can also:

• Ally yourself with the Sisters of Mercy. Each of their villages gives +5% per turn, which can add up to a huge bonus (healing 1/3 of your hp per turn with 5 or 6 such villages).
• Get a hero (necrophages or sisters of mercy) with a skill that boosts % healing per turn).
• Win the Legendary Deed that gives you Intelligence Corps for a flat +20% per turn.
• Build the Medical Center and/or Inoculation Station buildings in your city (for roughly 25% total).

These would all add up to a ton of regen; really the idea is that 5% is slow enough to really cramp strategic movements, because it's a painfully long 20-turn process to heal your troops if they get badly hurt - but by the time you're up to 25% or so, troops can fully heal in a mere 3-4 turns.

So the purpose of having all these different ways to heal your troops is that they cover each other if one of them becomes unavailable - if you can't (or strategically don't want to) get the necrophage hero, you can grab a different source of regen to get by. If the enemy grabs all the sisters-of-mercy villages, you can invest in the technologies - if you have the sisters, you can completely skip those techs/buildings and get ahead other ways.

You could stack everything for a wacky 60-70% regen per turn, but it's really not much better than 25% - by the time you reach 25% or so, you're healing in a few turns, and your meaningful military power is less about weathering repeated assaults, as it is about your units not getting killed during an individual assault - as the old saying goes, you can't heal being dead.

This is also because usually you're only up against a few armies; you're not withstanding some constant onslaught - if you survive to heal at all, you've almost always killed many/all of the enemy fighters in their army, and usually they only have a few armies in any given war (and will sue for peace after those die).