KeyForge is played over a series of turns in which you, as the Archon leading your company, use the creatures, technology, artifacts, and skills of a chosen House to reap precious Æmber, hold off your enemy's forces, and forge enough keys to unlock the Crucible's Vaults. You begin your turn by declaring one of the three Houses within your deck, and for the remainder of the turn you may play and use cards only from that House. For example, if you take on the role of the Archon Radiant Argus the Supreme, you will find cards from Logos, Sanctum, and Untamed in your deck, but if you declare "Sanctum" at the start of your turn, you may use actions, artifacts, creatures, and upgrades only from Sanctum. Your allies from Logos and Untamed must wait.

Next, you must strive to gain the advantage with a series of tactical decisions, leveraging both the cards in your hand and those in play to race ahead of your opponent. If you wish to weaken your rival's forces, you may send out your allies to fight enemies on the opposing side, matching strength against strength. Otherwise, you may choose to use your followers to reap, adding more Æmber to your pool.

Notably, no card in KeyForge has a cost — choosing a House at the start of a turn allows you to play and use any number of cards from that House for free, leading turns to fly by with a wave of activity! Yet balance is key. If you simply reap more Æmber at every opportunity, your rival may quickly grow their team of minions and destroy yours, outpacing your collection and leaving your field barren. But if you focus on the thrill of the fight alone and neglect the collection of Æmber, you won't move any closer to your goal! If you succeed in finding a harmony within your team and have six Æmber at the start of your turn, you'll forge a key and move one step closer to victory. The first to forge three keys wins!