Russia returns to its Civ VI identity of turning Tundra into genuine infrastructure — a Culture-and-Science hybrid built around territory no other civilization wants, backed by a real Blizzard-warfare edge.
Russia's Modern-Age kit centers on Tundra development — Farms in Towns gain Food (and later Production on Tundra specifically), Urban Districts in Cities gain Gold (and later Culture on Tundra), and units are immune to Blizzard damage while enemy units in Russian territory take increased damage from the same storms.
The Cossack is a unique Cavalry unit that doesn't replace the standard Cavalry line — you can build both — and gets increased Combat Strength while fighting in friendly territory. The Katyusha Rocket Launcher is a unique Artillery unit with increased Movement but reduced Combat Strength, carrying the Splash keyword that damages every enemy unit adjacent to its target.
The Obshchina is a unique Improvement granting Food from adjacent Farms and extra Culture if built on Tundra; it can't be built adjacent to another Obshchina. The associated Wonder, the Hermitage, adds Culture to Cities with a Great Work slotted, and must be built on Tundra.