Tannenberg (PC) Free @ Epic Games

Very Positive reviews on steam:
store.steampowered.com/app/633460/Tannenberg/

Tannenberg brings the massive battles of the Eastern Front in WW1 to life with 64 players fighting for control of key sectors of the battlefield, each one offering a distinct strategic advantage. Warfare between the Russian Empire, Germany, and their allies offers a fresh experience for first person shooter players and history enthusiasts alike.
There are seven squads, 50+ weapons, eight large maps that give players tactical freedom, and a 64 player game mode with full AI bot support so you can experience epic battles at any time!
Authentic WW1 FPSThis historical game takes place across the lakes, forests, mountains and snowy plains of the Eastern Front - it was inspired by the Battle of Tannenberg in 1914, one of the most iconic encirclement battles in history. Players will be able to master a range of authentically modelled equipment brought to the field by Russian Frontovik and Cossack squads, the renowned Latvian Riflemen, or the Roumanian infantry squad. Alternatively they can join the Central Powers to serve in an Austro-Hungarian K.u.K. unit, with the German Infanterie, or in the Bulgarian rifle section.
Maneuver Game ModeThe exciting Maneuver game mode reflecting the nature of war on the Eastern Front, as 64 players battle across large maps where the objectives and battle lines are always shifting. Survive the deadly battles by working together with your four man squad and utilizing your distinctive skills. There is a wealth of historical detail including realistic WW1 weaponry, authentic uniforms, horrendous gore, and maps based on real battlefields.
Key Features

• Authentic WW1 atmosphere; accuracy in everything from maps and weaponry to uniforms
• Tactical squad-based FPS; play as Russian, Roumanian, Latvian, Austro-Hungarian, German and Bulgarian troops
• Wide-ranging landscapes; large maps each with weather variants from snow to summer sun
• 64 player Maneuver game mode; capture strategic sectors in grand battles of movement
• Never fight alone; squad gameplay and AI bots for Maneuver so you can join epic battles at any time

Carefully ResearchedWe recreate the atmosphere of the Eastern Front with the same level of accuracy as seen in Verdun. Extensive research has been conducted, with uniforms recreated to the tiniest detail and weapons modelled to exact references. The maps use realistic props and terrain layouts based on locations from the hilly forests of Galicia to Polish villages subjected to scorched earth tactics and more!
Other games in the series are Verdun, set on the Western Front, and the upcoming Isonzo, which lets players experience mountain warfare on the Italian Front!