Choose eight unit cards: two Core cards, ready from the start; three Workshop cards and three Spire cards, which unlock in the match. Your bases mine alloy on their own. Spend it on squads, tech and outposts, and raze every enemy base to win. Both players see each other's decks, but not each other's armies: you see only what your units and bases see, and a scan. At 2:00 the relay in the middle comes online: stand on its ring unopposed to take it, for more alloy and a point a second at the time limit.
A campaign is a climb of battles from a starting deck: win to take new cards, find boons and depots on the way, and carry your core's damage up to the stronghold. One lost battle ends it.