Welcome back!
In RA20XX, the Soviet take a lot of inspiration from RA1. The reds reintegrate RA1's technology, most notably their usage of flamethrowers, mine layers and helicopter, while doubling down on their post-WWII industrial style (exemple : Flak Track and Katyusha). Overall, they are a balanced mix of RA1 and RA2's Soviet, excluding the weirder (and also useless) units design, like the Crazy Ivan or the Giant Squid. But for the purist, the most important thing to keep in mind is that RA20XX brings back their most iconic unit : the infamous Mammoth Tank!
==========Soviet Core Armament==========
==========Infantry==========
Conscript 
Role : Basic infantry
Weapon : AK-XX
Prerequisite : Barrack
Note : Slightly cheaper than its Allied counterpart (90 credit vs 100 credit).
Credit : Merophage
Flak Trooper 
Role : Basic infantry, Anti-Air
Weapon : Mobile Flak
Prerequisite : Barrack
Note : Identical to vanilla RA2's Flak Trooper.
Engineer 
Role : Engineer
Prerequisite : Barrack
Note : Capture building, repair building and bridge, as any engineer should.
Credit : Merophage
Terror Drone 
Role : Anti-Infantry, Anti-Spy
Weapon : Steel Blades
Prerequisite : Barrack
Note : The Terror Drone is not a vehicle anymore, as it now replaces the Attack Dog. It has slightly more armor than the Allied Attack Dog. Naturally, it can detect spies and will intantly kill infantry using its shap metal claws, transforming poor soldiers in a mist of blood (as shown above).
Credit : ZombyDragon (for converting the SHP from vehicle to infantry)
Pyroscript 
Role : Anti-Infantry, Anti-Building
Weapon : Portable Flamethrower
Prerequisite : Barrack + Radar
Note : Explode on death, damaging units nearby.
Credit : raminator
Tesla Trooper 
Role : Heavy infantry, Anti-Vehicle
Weapon : Tesla Gauntlet
Prerequisite : Barrack + Battle Lab
Note : Has more armor than RA2's Tesla Trooper, and can still buff Tesla Coil.
Credit : ImP_RuLz
Soviet Komissar 
Role : Infantry Support, Anti-Building
Weapon : Airstrike Flare
Prerequisite : Barrack + Battle Lab
Note : The Komissar instill fear to their comarades. Will buff infantry surrounding it (+25% armor and +25% damage). It has the authority to call airstrike on building.
Credit : Trans_C (for the unit), unknown for the aircraft voxel (subject to change if I can't find the author)
==========Vehicle==========
Heavy Miner 
Role : Harvester
Prerequisite : War Factory
Note : More armor and more storage than its Allied counterpart, but also slower.
Credit : B.A.Znd
Flak Track 
Role : Recon, APC, Anti-Air
Weapon : Light Flak Cannon
Prerequisite : War Factory
Note : Similar to vanilla RA2's Flak Track.
Credit : Shin.Peter.Pan
Hammer Tank 
Role : Main Battle Tank
Weapon : 125mm Cannon
Prerequisite : War Facotry
Note : More armor and more firepower than the Allied MBT, but slower.
Credit : Shin.Peter.Pan
Katyusha 
Role : Long Range
Weapon : x6 Rocket
Prerequisite : War Factory + Radar
Note : Fires 6 inaccurate rocket over a large zone. Rather low overall mobility.
Credit : Shin.Peter.Pan
Tesla Tank 
Role : Glass Cannon
Weapon : Tesla Sphere
Prerequisite : War Factory + Radar
Note : High firepower, low armor. Essentially a very accurate glass cannon.
Credit : Azri_Apoc
Piranha 
Role : Recon
Weapon : Dual grenade launcher
Prerequisite : War Factory + Radar
Note : Good versus infantry and light target. Won't deploy like the Siege Chopper.
Credit : B.A.Znd
Mine Layer 
Role : Defensive Support
Prerequisite : War Factory + Service Depot
Note : Deploys mines on the battlefield, detect cloaked at short range and is immune to enemy mines.
Credit : Azri_Apoc (modified)
Mammoth Tank 
Role : Heavy Tank
Weapon : Dual 125mm Cannon and Mammoth Tusk missile
Prerequisite : War Factory + Battle Lab
Note : Uses its two weapon at once. Replaces RA2's Apocalypse Tank.
Credit : MigEater
Mobile Warfactory 
Role : Mobile unit production
Prerequisite : War Factory + Battle Lab
Note : Deploys into a lighter War Factory which passively repairs nearby vehicle. Very useful to control an area in deep enemy territory.
Credit : Damfoos for the voxel, xuetianyi for the building
Kirov Airship 
Role : Heavy Balloon Hover
Weapon : Bombs
Prerequisite : War Factory + Battle Lab
Note : Pretty much RA2's Kirov with a freash coat of paint.
Credit : Shin.Peter.Pan
MCV 
Role : Base expansion
Prerequisite : War Factory + Battle Lab
Credit : Longwall
==========Building========== 
Credit : Radar Dome and Missile Silo by MadHQ, kenosis (Passive Service Depot's repair ring), Flak Cannon by Shin.Peter.Pan.
Most of the buildings are very similar to RA2's. Only those with new mechanics will be showcased in detail.
Flame Tower 
Role : Anti-Infantry Defense
Weapon : Large Flamethrower
Prerequisite : Barrack
Note : Very efficient against infantry, has a large AoE. Explodes violently when destroyed.
Credit : Merophage
==========Superweapon==========
Spy Plane
Role : Visibility
Prerequisite : Radar
Note : Less speed than the vanilla RA2's counterpart, but each camera click will reveal more.
Credit : B.A.Znd
Emergency Repair
Role : Defensive Support
Prerequisite : Battle Lab
Note : Instantly repair vehicle in a 3x3 zone. Takes 5 minutes to charge.
Iron Curtain
Role : Defensive Support
Prerequisite : Iron Curtain
Note : Renders friendly vehicle invulnerable for a few seconds, as in RA2.
Tactical Nuke
Role : Offensive Support
Prerequisite : Missile Silo
Note : Ultimate destruction power. Will now do a bit more damage against smaller buildings.
Credit : DonutArnold
==========Allied Update==========
That covers it for the Soviet forces. The navy will be revealed much later, in part with the Allied's. But this update is not finished yet! There has been a few modifications to the Allied since the last update.
First of all, the European Union's flag as been changed. It now reference Generals 2's EU. As the subfaction in RA20XX is inspired, in part, by this faction, it seemed justified to have similar flag.
Since the Pacific Shogunate's techtree is still being worked on, the Orca Hunter's voxel was changed.
Credit : mustang
So that is all for now! Next, I'll be showcasing the Soviet subfaction's armament.
Untill next time.
