gaunt estuary
I've seen plenty of suggestions of bringing back invasions already. I just wanted to add that I personally think it would be a great idea for invasions to be implemented as a weekend event alongside generic 2x SP boosts. Maybe on a cycle like 2x SP -> rebel invasion -> silver wolf invasion -> raider invasion.
It would be a great way to incentivise players returning to the game at least on a weekly basis, the same way a lot of modern Freemium type mobile games like Clash Royale does it.
gaunt estuary
Also had a few invasion theme concepts I wanted to share so I'm putting them here.
Gun Runners
Roster: Rebels
Theme: High dodge, mobility vehicles with some elite infantry support.
Example units: Dune Rider, Commando, Aces 650cc, Railgun Buggy, BC-3 Cobra
Chaos Insurgency
Roster: Rebels, Rioters
Theme: Frontier civilians provoked into rioting against the outpost by rebel spies.
Example units: Frontier Minuteman, Field Agent, Frontier Chucker, Guerilla, Special Agent
Furious Road
Roster: Raiders, Silver Wolves
Theme: Raider mounts and Silver Wolf vehicles with light infantry support. Mad Max reference
Example units: Wolf Pickup, Mammoth Rider, Wolf Cruel Bus, Raider Skirmisher, Wolf Fury
Rebel Bombardment
Roster: Rebels
Theme: Static artillery emplacements layered behind defensive fortifications
Example units: Light Artillery, Sandbags, Rocket Truck, Armored Fortress, Mammoth Artillery
Controlled Outbreak
Roster: Infected, Mystery Troops
Theme: Infected hordes under the loose control of mysterious evil scientists.
Example units: Enemy Creeper, Laser Technician, Enemy Hunter, Railgun Tech, Enemy Collosus
gentle slate
This is a really good idea
You could also do like:
Rebel Armored Column (tank strike)
Raider Outriders (raptor riders, mammoth tanks, infantry)
Critter stampedes