Star Scum is a deckbuilding card battler mixed with a tactics game where two ships battle each other using cards, units and ship equipment. Players take turns using their command points to play cards and command their units and ship equipment in battle. They must balance offense and defense and make careful use of their command points to outwit their opponent and destroy their ship's core.

The game has two modes: a singleplayer roguelike and a more balanced multiplayer mode.

In the singleplayer roguelike mode, you start with a basic deck and move across a map, building your deck from the cards of your defeated enemies. Players travel from station to station, upgrading their ship, buying new cards and picking up and delivering cargo cards between stations.

In the multiplayer mode, players build custom decks from all available cards and battle each other in ranked online battles. A local AI battle mode is also available for practice.