Tower Defense

Creeps walk the road from the left edge to your gate on the right. Tap a square beside the road to build a tower - Arrow, Cannon or Frost - and towers fire on anything in range, earning coins to build and upgrade more. Each creep that reaches the gate costs a life. Send the waves when you are ready; hold all twenty with lives left to win.

You start with 120 coins and 10 lives. Tap any square beside the road, then pick a tower to build there. Towers fire on their own at anything in range, and every creep they stop pays coins.

• Arrow (25) - quick shots at one creep. The cheapest way to start.
• Cannon (40) - slow, but every shot hits the whole group around its target.
• Frost (35) - barely hurts, but chills everything near it to half speed, so your other towers get more shots.

Tap a tower you have built to upgrade it (twice, up to level 3) or sell it for 70% of what you spent. A tower you have picked shows its range on the board.

There are three kinds of creep. Scouts are the plain ones. Runners are fast and fragile. Brutes are slow and armoured - every hit does 3 less damage, so a wall of level-1 Arrows cannot hold them, and one that reaches the gate costs two lives.

Nothing moves until you tap Send wave, so take your time building between waves. You can also call the next wave early while one is still on the road - riskier, but it scores extra points. Hold all 20 waves to win; lose your last life and the gate falls.

Touch: tap anything on the board to use it. Every button and key is at least 44px tall, so it works with a thumb. The squares of a board are as big as the screen allows - on a small phone some of them are smaller than that, which is why the keys and the number pad, not the squares, are what you type with.

Keyboard: Tab moves between the controls and Enter or Space activates the one you are on. That covers the buttons the game screen always has - Pause, Restart and this page's link - as well as anything the board adds.

Pause stops the clock and freezes the board; Restart gives you a fresh one.

Your score is the points you have when the game ends. Higher is better.

Play as often as you like. Every game is saved on this device, and your best turns up on the scoreboard.