After finish the campaign on insane, I have to say that the campaign is not balanced for this difficulty. Enemy throw a lots of things at you and you have low income which force you to play defensively and make mission last forever. Beside that many mission is impossible if you don't clear the map before getting your base because once you get your base, enemy will come from all side of the map with about 200 or more pop each wave and you don't have anything to do about it. Luckily the enemy is stupid and just attack move to our base so we can abuse that to win.
Some of the mission that feel imposible is 4th and 8th of GDF and 3rd of DYN. And coincidenly all of them are timed defense that don't have a proper prepare time and I hope the Veti campaign don't have any mission like that.
So if you are going to do campaign on insane there is something to notice:
-In many map enemy is passive before you finish the quest that give you the base which make clear them easier.
-Clear the map before doing the main quest and processing is advised if possible because it reduce the number of enemy that will attack you in some mission and make side quest much easier in other mission. Also you never know if triggering the next quest increase enemy spawn rate or not so always prepare.
-Elite unit (max tier veterancy) can regen which mean you can use your unit to clear a camp, regen then continue until you clear out the map which out the need of a base.
-Some mission enemy attack allied base which in those case get the base soon is better than clearing the map first. But those mission are rare.
-If you have spare technician or engineer, capture a enemy rig or refinary help you have money to deploy ability if you don't have a base
-Always use high ground if possible because enemy don't have vision force them to move close before start shotting.
Now come to the guide for each faction:
*GDF: Many people say GDF is easier, but I don't think it is entirely true. They have more tool but there tank is paperthin and get oneshot by Porcubine and melted by Voltatic make some mission hard.
-Importance Upgrade: Regen for Infantry and Vehicle armory upgrade is importance if you want to clear the map before getting your base.
-Defense: Trebuchet, Laser Turret and Engineer is the combo here. You may add Tempest or Haywire to add debuff on the enemy but not really neccesary. (2-5 Treb depend of mission with 5-10 Laser Turret and you can safely ignore that chock point, remember to replace Engineer if he die).
-Elite team (The one you should focus on level up first in no base mission): Sniper and Drone Assassin are strong specialist, Hunter Tank and Trebuchet is good vehicle, and for Infantry anyone use drone is good.
-Infantry: Drone Operator and Drone Mauler is both good as enemy focus on drones. Other isn't good in campaign so just ignore them or you can play them for fun.
-Vehicle: Hunter Tank is decent but GDF don't have other option. Trebuchet is tougher, deal more damage especialy to infantry and have siege mode but move super slow, still the best tank. Scramble is good as attacking squad with micro, fast, stealth, high damage and long ranger, down side is they are super fragile. Other is sitiational.
-Aircraft: Drone Command Unit outshine all other airplane in campaign, they are basically Carrier in Starcraft and one you have enough, nothing can stop you. You can also put Drone Operator in Skycrane as a replacement before unlock Drone Command Unit if you really want to use it.
-Specialist: Sniper is really strong anti infantry and scouting. Drone Assasin is strong anti vehicle. Riot Medic is healer and can also be used as tanker. Other 2 is situational.
-Note: It is good to steal DYN Construction Yard to get the plans even if you don't use enemy's unit.
*DYN: DYN don't have as much tool as GDF but some of their tool are strong. Also you might want to build 3 Contructions Yard at some point to get all 3 plans active.
-Good Upgrade: Improved Reliability is good as it make your Vehicle tankier.
-Defense: Even though DYN doesn't have as much tool as GDF, 1 or 2 deployed Savage Center with enough Rocket Turret and Security Plan will stop anythings (don't worry about Trebuchet as AI don't know how to use them). Though you need to micro them when attacked by Drones. You can add Voltaic Railgun to the defense if you like. SAM is situational as Rocket Turret is good enough against air already.
-Elite Team: Operative, Commando and Machinist. Then Voltaic and Boar Tank. DYN don't have passive regen but they have ability to build a healing building for infantry and their tank is more tanky than GDF to compensate.
-Infantry: DYN infantry is only good at one thing (anti infantry or anti vehicle) and they are not super good in insane campaign. Assault Gunner is decent anti air if you don't want to play Havoc.
-Vehicle: Voltaic Tank is super good, high damage, high health, AoE but they are unlocked late in the campaign. Boar is a good tank, less range but more tanky than the Hunter of GDF, fully upgraded boar (doctrine and armory) can 1 vs 2 Hunter, they lack damage to infantry but can run over them anyways, and also as most GDF units use rifle, they can't pierce boar armor at all. Porcupine is good artilery that shot hard and don't require set up. Havoc is a good additional that help DYN deal with air unit. Savage Van is good at repairing and can be deploy as Savage Center help you build defense anywhere on the map.
-Aircraft: Really situational. Not as good as GDF and no aircraft that can both attack air and ground. Maybe if you want to bomb something then return.
-Specialist: Both Operative and Commando is good stealth unit that can hit both Vehicle and Infantry. Machinist can repair in area like Savage Van but cheaper and have strong attack. The other 2 is situational.
Eventhough finish insane with all sidequest is possible with the strategy I said, if you still feel insane is too hard with side quest, you can do it without the side quest and replay on easy to get that quest.
