Tower One is a tower defense game where your towers gain experience and level up by defeating the monsters that come running through the path towards your village.
Each tower gains stat points (damage, attack speed, range, splash), and skill points (slow, crit, fire, etc.) when leveling up, and you choose to upgrade whatever you want.
All buildings (tower, village, houses, farms, tombs, corpses, planted trees, etc.) also level up and have their own stats and skills.
Balance spending resources into towers or building your economy (houses, farms, get the merchant, implement taxes on your poor villagers, etc.).
When a mob reaches the village you loose lives, and a corpse appears on the map that we can plant a tree on it (unique towers which level up or 'grow' on their own) or bury it to convince his soul to help up as a friendly ghost on our battle.