The game is lacking defensive structures. A few simple structures could add some depth to the game, while preserving it's simplicity.
Watchtower: Unlocked in "Spiritualism" tech tree. It costs 12 stars, and gets defense bonuses when built on forest or mountain tiles.
Limitations: You may build 1 Watchtower per city.
Effect: The Watchtower has a range of 3 tiles, and will shoot a projectile at the highest HP target in range for 3 damage at the end of the belonging player's turn.
If the city the Watchtower belongs to is captured, the Watchtower's ownership is transferred to the new owner of the city.
Watchtowers have 35 HP, and 2 Defense. They get a defense bonus when built on forest/mountain tiles.External link →