Tap or click where to go, or drag to draw a route and the assassin follows it. Get close and press Strike (Space, or tap the guard): from behind a blow kills, but a guard who faces you alert, or any shotgunner, takes two. Take down every target to clear the level.
Guards see in a cone; walls and crates block it. Inside a cone their meter fills, and a full meter means gunfire. Darkness makes them much slower to notice you: watch the light gem. Guards hear footsteps right behind them, follow bloody footprints, raise the alarm when they see a friend fall, come at you from several sides and cover the doors; dogs follow your scent and cameras sweep the rooms (strike one to smash it, loudly).
Double-tap (or Shift) to Shadow Step a few metres, untouchable for a moment; you hold two. You run faster in the dark, and quick chains of kills pay a combo bonus. Throw a pebble (right-click, Q or the button) to lure a guard away. Found bodies raise the alarm.
Keys: WASD move · Space or F strike · Shift Shadow Step toward the cursor · Q pebble · Z or the wheel to zoom · R restart · L levels · P pause · M sound. On a phone, pinch to zoom.