Hammer & Sickle is a turn-based strategy game with role playing elements that uses the Silent Storm engine and universe. The year is 1949, with the Cold War between the US and Soviet Union looming and both sides uneasy at the thought of an atomic war occurring. The player takes the role of a Soviet commando on an undercover mission to meet a contact in Allied-occupied Germany. However, things go badly for this meeting, leaving the protagonist without proper support, equipment, and identification papers. Behind Allied-occupied lines, the player must attempt to stop a rogue third party intent on initiating World War III between the US and Russia.

Players can choose to start with one of 6 player classes: Soldier, Grenadier, Scout, Sniper, Medic, and Engineer. Additionally, there are opportunities throughout the game to recruit additional characters to round out the party's abilities. The game itself features a branching plot where the player's actions and dealings with NPC's can have serious consequences later on. For example, an intelligent character may be able to talk his way out of a situation, and killing Allied soldiers may prompt more patrols later on and slide the situation towards World War III.

Hammer & Sickle also features heavy squad-based combat, and it inherits the turn-based engine from Silent Storm. Players spend Action Points to perform various actions in battle each turn, while the enemy does the same. The engine also models realistic looking physics that feature ragdoll animations, bullet ricochet, and destructible environments. As for available equipment, there are 90 weapons and variants that can be found or bought.