Frost Line

Frost Line is a tower defence played out on a polar night. Packed-snow trails run across blue-white snowfields, over frozen lakes and between ice cliffs, and at the end of every trail stands a little village of igloos with warm orange windows. An aurora rolls across the sky the whole time, tinting the snow green and violet, and it shifts colour as the waves climb.

Five towers, three tiers each. Snowball cannons crewed by penguins lob splashing snowballs and are the only thing that cracks a snow golem's armour. A walrus works the ice beam, a continuous ray that fills one raider's freeze meter until it turns into an ice statue; hit the statue and it bursts into shards. The yeti's harpoon post throws a long bolt that punches through a whole line and drags the light ones a step back down the trail. A snowy owl keeps the aurora totem, which never fires a shot but widens and quickens every tower around it, and at tier three the freeze jumps from one raider to the next. Igloo barracks send out two penguin guards who simply stand in the way.

The raiders come in six shapes: arctic foxes on sleds that dodge the first harpoon, seals that slide at double speed wherever the trail crosses ice, armoured snow golems that cannot be frozen until the armour is gone, ice bats that fly straight over your cannons, frost wisps that heal everything around them, and a woolly mammoth that smashes through penguin guards and sheds fur across the lane. Blizzards blow in every few waves and halve the range of any tower not standing near an aurora totem. Twelve hand-laid maps across three regions, fifteen to twenty-five waves each, a boss every fifth wave, three stars for a map held without losing a single life, and an endless run on the last map for anyone who still wants more.