The Soviet spritepack adds 16 more Soviet sprites in the game.

Tanks:

BT-5
BT-7
T-28
T-34
T-44
KV-1
KV-2
IS-2

Aircraft:

Mig-3
Mig-9
Lagg-3
Yak-4
Sukhoi SU-2

Ships:

Gangut-class Battleship
Kirov-class Heavy Cruiser
Leningrad-class Destroyer