Games set in a Slavic setting? Games set in a Slavic language? Games made by Slavic developers?
I’ll focus on developers.
CD Projekt Red (Poland)
The Witcher Series
Cyberpunk 2077
Bohemia Interactive (Czech Republic)
Operation Flashpoint Series
ARMA Series
DayZ
Take On Series
Vigor
Ylands
Warhorse Studios (Czech Republic)
Kingdom Come: Deliverance
Oxymoron Games (Czech Republic)
Project Hospital
Beat Games (Czech Republic)
Beat Saber
Techland (Poland)
Dead Island Series
Dying Light Series
Flying Hog Wild (Poland)
Shadow Warrior Series
4A Games (Ukraine)
Metro Series
GSC Game World (Ukraine)
S.T.A.L.K.E.R. Series
Cossacks Series
Vostok Games (Ukraine)
Survarium
Cauldron (Slovakia)
“Cabela’s” branded hunting games
The Farm 51 (Poland)
NecroVisioN Series
Outfit 7 (Slovenia)
Talking Tom Series
Wargaming (Belarus, formerly)
Massive Assault Series
World of Tanks Series
World of Warships Series
World of Planes Series
Haemimont Games (Bulgaria)
Tropico Series
Imperium Romanum Series
Grand Ages Series
Snapshot Games (Bulgaria)
Phoenix Point Series
Croteam (Croatia)
Serious Sam Series
Little Green Men Games (Croatia)
Starpoint Series
AI Interactive (Bosnia and Herzegovina)
The Enchanted World
Juju Frog
Trivaders
Dragon of Bosnia
Archangel Studios (Montenegro)
Bleak Faith (WIP)
Nordeus (Serbia)
Top Eleven Football Manager
Heroic - Magic Duel
Eipix Entertainment (Serbia)
Dark Parables Series
X3M Games (North Macedonia)
Impossible Space
Targem Games (Russia)
Crossout
Atom Team (Russia)
Atom RPG
Nival (Russia)
Blitzkrieg Series
Etherlords Series
Heroes of Might and Magic Series
Silent Storm Series
Battlestate Games (Russia)
Escape from Tarkov
Gajin (Russia, formerly)
War Thunder
Alexey Pajitnov (Russia)
Tetris (1984)