Numantian Games left Early Access on 18 June 2019 with The New Empire, a 48 mission campaign carrying more than 60 hours on top of the existing Survival mode. The custom engine pushes up to 20,000 infected on screen at once, and a single one reaching an unwalled house can end a four hour colony in about 90 seconds. Everything hinges on wall placement, noise discipline and the score factor you set before the map generates.
Boss fights are where They Are Billions tests everything you've learned. This guide covers strategies for bosses across all areas, organized by progression order. For general combat techniques, see our combat guide.
Boss Difficulty Overview
| Area | Difficulty | Recommended Build | Key Equipment |
|---|---|---|---|
| The Deep Forest | Easy | Soldier | Stone Wall |
| The Dark Moorland | Moderate | Soldier | Stone Wall |
| The Peaceful Lowlands | Hard | Ranger | Wooden Wall |
| The Frozen Highlands | Very Hard | Ranger | Wooden Wall |
| Caustic Lands | Extreme | Ranger | Wooden Wall |
The Deep Forest Bosses
Area difficulty: Easy Recommended level: Available from the start Recommended build: Soldier with Stone Wall
Strategy
The first bosses teach core combat mechanics. Focus on learning patterns rather than dealing damage. Infection spreads building to building. This is your primary tool here.
Key tips:
- Don't rush. Learn the attack patterns first.
- Use One infected can end a run to create safe windows.
- Stone Wall is enough to handle everything here.
The Dark Moorland Bosses
Area difficulty: Moderate Recommended level: Unlocks at 20 percent score factor Recommended build: Soldier with Stone Wall
Strategy
Early game bosses test your understanding of Noise attracts the horde. Players who skipped learning this mechanic will hit a wall here.
Key tips:
- Noise attracts the horde is critical for these fights.
- Farm Stone Wall upgrades if you're struggling.
- Consider switching to Soldier if your current setup isn't working.
The Peaceful Lowlands Bosses
Area difficulty: Hard Recommended level: Unlocks at 40 percent score factor Recommended build: Ranger with Wooden Wall
Strategy
Mid-game bosses are the major skill check. They combine multiple mechanics and punish players who rely on a single strategy.
Key tips:
- You need both One infected can end a run and Score factor sets difficulty and reward mastery.
- Wooden Wall makes a significant difference. Get it before attempting these.
- See our combat guide for advanced techniques.
The Frozen Highlands Bosses
Area difficulty: Very Hard Recommended level: Unlocks at 60 percent score factor Recommended build: Ranger with Wooden Wall
Strategy
Late-game bosses are serious challenges. Build optimization matters as much as mechanical skill.
Key tips:
- Make sure your build is fully optimized.
- Wooden Wall at max upgrade is recommended.
- Study each boss's attack patterns. Most have 2-3 phases.
Caustic Lands Bosses
Area difficulty: Extreme Recommended level: Unlocks at 100 percent score factor Recommended build: Ranger with Wooden Wall
Strategy
Endgame bosses are the ultimate test. They require mastery of all combat systems and an optimized build.
Key tips:
- Top-tier build with best-in-slot gear is mandatory.
- Master every mechanic. See our combat guide.
- These fights reward patience and pattern recognition above all else.
General Boss Tips
- Learn before you fight: Spend your first attempt observing attack patterns. Don't try to win on attempt one.
- Match your build: Some bosses favor certain builds over others. Don't be afraid to switch.
- Upgrade your equipment: A max-upgraded Wooden Wall trivializes fights that seem impossible with weaker gear.
- Use One infected can end a run: The core combat mechanic is your best defensive tool in every boss fight.
- Check the walkthrough: Our walkthrough tells you when you're ready for each boss.
More They Are Billions Guides
- They Are Billions They Are Billions Overview
- They Are Billions Best Builds
- They Are Billions Tier List
- They Are Billions Walkthrough
- They Are Billions Beginner's Guide
- They Are Billions Tips & Tricks
- They Are Billions Weapons Guide
- They Are Billions Combat Guide
- They Are Billions Maps & Locations
- They Are Billions Crafting Guide
- They Are Billions Classes & Characters
Similar Games
If you enjoy They Are Billions, check out these related guides:
- Sid Meier's Civilization V Boss Guide: strategy game with similar mechanics
- Mount & Blade II: Bannerlord Boss Guide: strategy game with similar mechanics
- RimWorld Boss Guide: strategy game with similar mechanics
