Tower Defense Example

Arcade Transitional

ecs

Transitional example: This example uses an older Cougr pattern and is preserved for compatibility reference. For the current recommended approach, see snake.

A minimal tower defense game implemented as a Soroban smart contract using the cougr-core ECS framework. This example demonstrates wave spawning, enemy path progression, tower attacks, health reduction, and win/loss conditions.

Features

Wave Spawning: Enemies spawn in waves with increasing difficulty
Deterministic Path Progression: Enemies follow a predefined path toward the base
Tower Placement: Three tower types with different stats (Basic, Sniper, Splash)
Attack Resolution: Towers automatically target and damage enemies in range
Win/Loss Conditions: Survive all waves to win, or lose when base health reaches 0

ECS Architecture

Components

Component	Fields	Purpose
`EnemyComponent`	hp, max_hp, speed, path_index	Represents enemies moving along the path
`TowerComponent`	kind, range, damage, cooldown	Represents static defenders
`WaveComponent`	current_wave, total_waves, remaining_spawns	Tracks wave progression
`BaseComponent`	health, max_health	Tracks survival condition
`GameStatusComponent`	status, tick_count, enemies_killed	Tracks game state

Systems

WaveSpawnSystem: Spawns enemies according to wave configuration
PathProgressionSystem: Moves enemies along the predefined path
AttackResolutionSystem: Towers target and damage enemies in range
BaseDamageSystem: Reduces base health when enemies reach the end
EndConditionSystem: Checks win/loss conditions

Contract API

`fn init_game(env: Env)`

Initializes a new game with default settings.

`fn place_tower(env: Env, x: u32, y: u32, tower_kind: u32) -> bool`

Places a tower at the specified coordinates.

tower_kind: 0=Basic, 1=Sniper, 2=Splash
Returns true if placement was successful

`fn advance_tick(env: Env)`

Advances the game by one tick, executing all game systems.

`fn get_state(env: Env) -> GameState`

Returns the current game state including base health, wave info, and status.

`fn is_finished(env: Env) -> bool`

Returns true if the game has ended (won or lost).

`fn get_result(env: Env) -> u32`

Returns the game result: 0=active, 1=won, 2=lost.

Setup

Navigate to the example directory:
```
cd examples/tower_defense
```
Build the contract:
```
cargo build
```
Run tests:
```
cargo test
```

Validation Commands

cd examples/tower_defense
cargo fmt --check
cargo clippy --all-targets --all-features -- -D warnings
cargo test
stellar contract build

Game Configuration

Map Size: 10x10 grid
Path Length: 8 waypoints
Total Waves: 5
Enemies per Wave: 5
Base Health: 100
Enemy Base Damage: 10

Tower Stats

Tower	Range	Damage	Cooldown
Basic	2	10	1 tick
Sniper	4	25	3 ticks
Splash	1	15	2 ticks

Cougr Documentation