A fast-paced arena game of movement, pressure, and permanent construction. Players move across a 12×12 black-and-white grid, drawing cards based on where they land. Health is both life and currency. Towers change the map. Nothing you build protects you from the system itself.
Keystone is about movement, pressure, and commitment. The board never remembers what happened. Cards resolve immediately and get discarded. The arena has no memory of you. Only Towers persist — and building them costs the same resource that keeps you alive.
Health is your fuel. Spend it to build. Lose it to threats. The tension is in that tradeoff the whole game.
The board is a 12×12 checkerboard. Black squares draw from the Yin deck — pressure, damage, disruption. White squares draw from the Yang deck — recovery, momentum, opportunity.
You never know what you're drawing until you land. The Yin deck is heavy with Threats (29 of 52 cards). The Yang deck is heavy with Supplies (20 of 52). The asymmetry rewards navigating toward white squares when you need to recover and punishes you when you get trapped on black.
Cards resolve immediately and are discarded. No board state. No memory. The arena doesn't know you were here.
Towers are the only permanent things in Keystone. You place tiles by ending your movement on a square and spending 1 Health per tile — up to 2 tiles per turn. Stack 7 upright tiles and you win immediately with the Capstone.
A sideways tile caps a tower. Capped towers can't grow, can't be recaptured, but are still landable and PvP can happen on them.
Building costs Health you might need to survive. That's the whole game.
PvP triggers when you land on another player. Both roll d6. Higher roll wins. Loser takes damage equal to the difference. Ties deal nothing. The winner can move 1 additional square.
Shooting: roll 1d6 for range, pick direction, first opposing player in the line takes 1 damage. Can't shoot through towers.
Movement is 1d6 per turn. Stop early if you want — unused MP is lost. Passing through squares does nothing. Cards only trigger on landing.
Win immediately if: you land on an Exit with Health ≥ 1, your opponent dies, or you complete a Tower with 7 tiles.
Cooperative: all players must escape. If any player hits 0, everyone loses.
Capture the Flag: team play, objective-based, Exits removed, flag carrier can't use Equipment or Momentum Supplies.
Team Score: PvP kills earn VP (1 per win, 2 for KO), defeated players respawn at Start with 10 Health.
Game length 20–30 minutes.