While it's for the previous game in the series, significant portions of Dinuvar's "Beginner's Guide to Chaos Galaxy" is still relevant and informative (take particular note of the 'Trading Damage Efficiently' section). You can read it here:
https://steamproxy.net/sharedfiles/filedetails/?id=2202048730

One of the most important tactical layer mechanics for how under-explained it is.

If a unit drops to zero 'power' (health), it explodes. However, dropping it to zero morale also makes it retreat (vanishing from the map), and can be considerably easier than killing it outright. Although this isn't always fully desirable, since the enemy officer (except aliens) keeps the retreated unit afterward if they win the battle or when they respawn.

Even before retreating, units with 70 or lower morale take an additional 20% of base damage ('downcast' state), increasing to 40% of base damage at 30 or lower morale ('collapsing').

Flank attacks cause the target unit to lose 10 morale, even if all the shots miss or are blocked by shielding. Rear attacks and 'ambush' attacks (by dived submarines) cost it 20 morale. Map weapons (nuclear bomb, black hole gun, starkiller beam and artillery) cause 15 morale damage. Losing the flagship is a 50 morale hit to all remaining ships.

Keep in mind that the flagship and units close to it gain 5 morale at the start of every turn.

Units with the Indomitable passive do not take increased damage or retreat due to morale effects. Omnic Apocalypse also have a level 1 policy that negates all morale damage.

Unlike in CG1 with its random shield failures, the various defense systems in CG2 have a fixed number of hits they can take before they break and require repairs (the durability stat).

There are a few defense types:

• Beam Field: Negates beam weapons; generally found on large ships
  
• Magnetic Field: Negates projectile weapons; generally found on large ships
  
• Power Shield: Reduces damage of all weapons by 50%; generally found on mecha
  
• Carapace: Reduces damage of all weapons by 30%; found on some alien units and biomechs

The human shields must be used as a specific option when defending (instead of counterattacking or dodging), consuming energy to do so. This also means they can't be used against map weapons. Carapace is passive and works automatically against any non-DoT damage source.

Durability counts hits regardless of damage, so Machine Gun and mass-fired missiles/cannons are the fastest way to break defenses (as long as they hit).

To restore a damaged or broken shield, repair the unit with a support ship (or heal it, for aliens/biomechs). Repair from shipyard/arms factory, alien/biomech auto-heal, and most tactics skills don't count. Auto Repair passive counts; units with it will fully restore their own shields at the start of each turn, so if you don't have a way to bypass the shield, you may need to go for a morale kill.

This is a diplomatic superweapon. If a faction likes you enough, you can make them hate anyone else at no cost to yourself, even to the point of breaking alliances or vassalage and going to war, and take advantage of the resulting chaos. If they don't already like you enough (and aren't at war with you), just throw some surplus gold their way.

NPC factions will also sometimes use this on you; you can accept or reject their words to lower your relation with either the slanderer or their target.

The biomech units unlocked by alien research are some of the better units you can get (especially with all the buffs the rest of the research tree gives), often being stronger than human units. Their most notable advantages are: They can restore HP in-combat (whereas normal units require specific tactics skills for this), and they don't run out of energy.

List of biomech units and some notes on them:

• Chimera Warrior (mecha): Starter biomech. Low movement (4 base) and unremarkable attack power (slightly above basic mecha), but pretty hard to kill due to their high HP and carapace.
  
• Bionic Sporeboat (submarine): Starter biomech. The direct damage per turn with the spore isn't great, although it's also a guaranteed hit and causes corrosion. Big advantage is that it don't need to surface to attack. Comes with funny pog face.
  
• Healing Ball (support): Does what it says on the tin. Can go into asteroid belts, and also has reasonable HP so it takes a bit of work to kill when it's healing itself.
  
• Carapace Cruiser (warship): Decently fast (5 base), high HP, has carapace and self-heal. Bone Rifle does a lot of damage but has limited accuracy.
  
• Chimera Champion (titan): Basically a melee version of the cruiser. Comes with Chase for extra fun.
  
• Pterosaur Fighter (fighter): One of the best units in class. Stupidly fast (7 base) and hard to hit with 70 agility, and has self-heal. Acid Sprayer does a lot of damage and inflicts corrosion to boot.
  
• Parasite Carrier (support): The most OP unit in the game. Its parasite spore is a guaranteed 3-turn mind control on any unit it hits. High health, decently fast (5 base) and can teleport. Also has healing and a hypnosis ability, although you should be spending your turn either using or reloading the spore if you can.

(maybe I'll replace this with a brief strategy guide for each of the playable factions later)

Whichever faction you choose, I'd recommend setting the alien invasion direction to the opposite side of the map from where you are, unless you're experienced with the game and know how to do things like bait the aliens into enemy territory.

Northsky Fleet is probably the easiest starting faction, aside from being next to the default alien invasion point. It has a full six initial planets (twice as many as some of the other factions) and no enemies except the faraway Omnic Apocalypse, whom you can safely leave to others. Your faction leader Li Chengsong has 4-range lances, so can engage a lot of targets without counterattacks.

Lycurgus Corps has another easy start. You're next door to the Omnics but have no other enemies, a bunch of neutral planets are nearby, and by default the alien invasion is on the other side of the galaxy from you. Reliance on cannons for ranged combat is troublesome, but you also have good buffs for melee mecha, and the ram weapon on ships.

Omnic Apocalypse is a middling start. You're technically at war with the entire human galaxy; luckily, almost everyone has their own immediate problems. Use the opportunity to defeat nearby enemies, secure territory, and maybe negotiate truces with amenable factions. Your primary weapon types (railgun and wave cannon) are excellent, and you have some very strong policies to research, so you can be a real late game powerhouse.

Emishi Pirates can be medium or hard depending on alien invasion direction. You have a bunch of free real estate all around you. Your enemies are Eastgalaxy and Southern Principality to the south and southwest, but be careful as Northsky is also likely to opportunistically declare war on you. Your main weapon type (missiles) can attack Imperials without retaliation by attacking in the blind spot between their cannon and lance ranges (attack from a chess knight's move away), and you have a policy and commander talent that gives damage buffs against Imperials. If the aliens come for you, try to bait them into Imperial territory.

Free Stars is a hard start, with only two planets' worth of economy and Tigerhill for an unfriendly neighbor. Invest in development and grab as many neutral planets as you can while fending off the Southern Principality. Once you have a decent cashflow, the Revolution faction mechanic lets you grab other people's planets (including those of 'friendly' factions) without fighting.

Eastgalaxy Company is also quite hard. You're a Tigerhill neighbor and the Emishi Pirates are likely to be coming down for revenge in short order (consider buying a truce ASAP). On the positive side, gold will cease to be a problem fairly quickly. When you've dealt with immediate threats, use bribery and Alienate to carve up the rest of the galaxy as needed.

(the following is from my experience with medium player econ bonus + medium AI econ bonus, or low + low; I can't speak to high-high or low-high runs)

Early game, your focus should be first and foremost be on building gold-producing structures: hive cities, civil ports, and some faction uniques. Gold gets turned into buildings, which make you more gold and supplies. It's also needed to buy military units and pay officer salaries. Officers get paid more as they level up, something to keep in mind when managing early game cashflow.

You'll also want to invest in some supply production (farms or mines) as well, to meet upkeep requirements for your current military and stock up for future wars.

Don't go buying lots of military units unless you need them. They cost gold that could be spent elsewhere, cost supplies to buy and further supplies to maintain.

A thing to keep an eye on is the unrest output of your planet (mouse over the unrest amount on the planet screen for a breakdown). Unrest lowers the planet's income (penalty scales linearly to 50% base income at 100 unrest), which applies to all outputs: gold, supplies, learning points, alien knowledge, and labor. Planets with high unrest can also spawn rebel fleets; these will be easily defeated if you have a halfway decent fleet nearby, but are otherwise quite annoying.
Build one or more leisure complexes to lower unrest. How many you need depends on what you build on the planet and how big it is; farms, mines, and hive cities add unrest, while laboratories don't. Some faction uniques lower unrest while others (like Lycurgus's training grounds or Free Stars' immigration office) raise it.
You can also make unrest go down by parking an officer on the planet, preferably one with a high Admin score. The Pacify People strategy skill can be helpful to get unrest on a particular planet under control.

Labor is a per-planet resource, unlike the other types. It's used to upgrade buildings, which is how planets grow in the long term. The Command Center on every planet generates labor, but an early farm or two will help speed things along.
Upgraded buildings generate more income but also more unrest, so make sure your leisure complexes keep up with your farms, mines and cities.
Protip: The Auto Update checkbox in the top right of the planet screen will enable automatic building upgrades across your empire.

Learning points are a tertiary resource. They unlock new policies (i.e. research) which is highly valuable, but not immediately pressing like gold and supplies are, so don't go overboard investing in them. If you're playing as Omnics, you'll have more knowledge than you know what to do with; spend some on skill chips for your officers.

Later in the game, gold becomes a lot more abundant than supplies, so your focus should shift to the latter.

Use the Set Base function on a planet (button is in lower-right) to move your fleet spawn point closer to the front line. This costs 10k gold the first time, increasing by 5k each time you do it.

You go twice as fast on starlanes, but only if the planets on both ends are controlled by you, an ally or a vassal.

Units captured from other factions aren't always useful since they don't come with the relevant policies, but can still have their uses, e.g. if they're compatible with a commander's talent or tactics skill. If you do have the right policies, go wild.

If the aliens are about to invade your territory, try to have a fleet lure them to your neighbors.

Even without access to the invading Blackdragon Spawns, you can unlock alien research by killing the space worms in the Sandsea (south to southwest region of the map).

It's often easier to let a competing faction soften up a minor faction for you, then move in to grab their planet for yourself.

While fighters add to a fleet's assault strength, they're considerably less efficient at it than mecha.


If a unit walks into a dived enemy submarine, its turn gets cancelled and the submarine gets a free ambush attack (being revealed in the process). Learning to predict likely enemy movement paths and parking dived submarines in their path is a useful trick.

Forts, although significantly buffed from CG1, are still generally weak on their own. They're most useful as meatshields for your fleet and to opportunistically finish weakened enemies, bleed morale with flank/rear attacks, or batter magnetic fields. At least they also don't cost upkeep. A few unlockable forts, like the Regent Forces' Tongguan, can also be quite powerful in their own right.

Attacking a unit from its front corners (directly left and right of the tile in front) counts as a frontal attack. However, attacking from the rear corners counts as a rear (not flank) attack. Useful for units with circle range weapons, especially cannons.

Instakill chance increases as the target's remaining HP decreases. Tempt chance increases as the target's morale decreases.

When using double attack tactics skills, the second attack will not be shielded against (except by carapace).