Every answer is a tower.

Sudoku Defense turns a Sudoku puzzle into a battlefield. Fill an empty square with the right number to grow a tower and earn credits. When you're ready, prepare your defenses and let the wave begin.

Solve first. Fight next.

Your recent placements shape the enemy route. Use the solve phase to build a strong position, then watch the board become a voxel battlefield. Need time to think? Open your gear to pause the action, or speed up a wave to 2× or 4×.

Build the tower you need.

Each tower has five module slots. Stack lightning, frost, splash damage, faster shots, and other effects—or mix them. Drag gear onto a tower, swap a module, or upgrade every tower with the same number at once. Number highlights show which towers an upgrade will affect.

Break a rule. Take a risk.

During a wave, a reserve seed lets you place an emergency tower—even if its number breaks Sudoku rules. That extra firepower comes with corruption, which gives later enemies more health. Decide whether the board can hold without it.

Open chests. Keep building.

Defeated enemies drop fragments and sometimes chests. Spend fragments to open them, then equip your new modules or save a temporary boost for a difficult wave. Between rounds, spend credits on upgrades or try the salvage slots. If a spin returns fewer credits than it costs, you also get a common module.

Choose your run.

• Campaign: up to 50 rounds, with puzzle and combat difficulty chosen each round.
  
• Locked In: keep your chosen difficulties for the whole run.
  
• Free Play: one puzzle and one battle.

Play with a controller, mouse, or touchscreen. Runs save locally so you can come back later.