Towerkeep

Enemies march along the dirt road from the spawn point toward your castle keep. Build guard towers on the empty ground beside the road to stop and destroy them. Every enemy that reaches the keep gate costs you lives; when lives hit zero, you lose. Survive all waves to clear the level.

### Core Resources
- Gold: Used to build and upgrade towers. You start with 200 gold, earn more by killing enemies, and passively regain +1 gold every 6 seconds during non-boss waves.
- Lives: Start at 20 (scaled by difficulty). Each leaked enemy reduces lives; zero lives means defeat.
- Coins: A persistent cross-level currency earned by playing, spent in the main menu to unlock permanent upgrades.

### Towers (4 types · the Four Guard Towers)
| Tower | Cost | Trait |
|-------|------|-------|
| Archer Tower | $50 | Single-target, fast attack, best all-round starter |
| Frost Tower | $55 | Slows enemies on hit, lower damage, for crowd control |
| Arcane Tower | $75 | Attack pierces up to 3 enemies at once, long range |
| Cannon Tower | $90 | Area splash (AoE) damage, high per-hit damage, slow fire rate |

### Tower Upgrades
Each tower can be upgraded to level 5, with 5 upgrade paths:
1. Armor: Ignore/reduce enemy armor
2. Damage: Increase attack power
3. Attack Speed: Shorten attack interval
4. Range: Extend attack range
5. Special: Enhance the signature effect (pierce count, slow strength, splash radius…)

Upgrade cost scales with level. At level 5 you can enable the tower's "auto-cast special". Tap a placed tower to open its info panel and upgrade or sell it (selling refunds 80% of cost).

### Skills (cast free by watching a rewarded video)
- Barrage: Deal 50 damage to all enemies on the field
- Frost Ward: Slow all enemies by 70% for 3 seconds
- War Chest: Immediately gain 50 gold

### Enemy Types
Goblin Grunt, Raider, Iron Brute, Siege Lord (Boss), Shadow Bat (ignores slow and some effects), War Priest (heals nearby enemies), Powder Imp (explodes on death), Death Warden (heals over time), Split Ooze (splits on death), Shieldbearer (shield absorbs damage).

### Difficulty
- Easy: enemy speed ×1.0, lives ×0.6
- Normal: enemy speed ×1.4, lives ×1.0
- Hard: enemy speed ×1.8, lives ×1.5

### Controls
1. Tap a tower in the bottom build bar to enter placement mode (green ring = valid / red ring = invalid).
2. Tap empty ground beside the path to place it; press ESC or right-click to cancel.
3. Tap a placed tower → upgrade / sell.
4. Tap a skill button (after watching an ad) to cast the skill.
5. Use the pause button anytime. On defeat you can retry or return to the menu from the results screen; clearing a level unlocks the next one.
6. Drag up/down on the battlefield to pan the view and check path segments hidden behind the bottom bar; taps still select/place towers (drag and tap are distinguished automatically, works with touch on mobile).