In Build a Boss you assemble a mechanical boss from guns and armor parts, then fight through waves for cash and gems. Early money is tight, so the fastest way forward is to buy one cheap weapon, clear the opening Scrapyard levels on repeat, and spend only on the upgrades that raise your clear speed.
Quick answer: Buy the Pea Gun for 90 Cash, place it on your boss core, clear early Scrapyard levels, claim every Free Rewards tab, then spend on Sharper Shots and Powder Load first.
Buy your first weapon and start fighting
Your economy only grows by winning battles, so the priority is getting a working weapon on the grid and entering combat. The Pea Gun is the intended first purchase because it points wherever the boss points, which makes aiming simple while you learn the movement.
Claim every Free Rewards tab for instant cash
The single fastest cash injection early on is the Free Rewards menu, opened from the top header. Login days, playtime, and social tasks together hand over thousands of cash and a stack of gems before you have won many fights.
| Reward | Payout |
|---|---|
| Day 1 | 500 Cash |
| Day 2 | 20 Gems |
| Day 3 | 1.50K Cash |
| Day 4 | 8 Gems |
| Play 30 minutes | 1.00K Cash + 4 Gems |
| Favourite the game | 300 Cash + 3 Gems + x1 Item |
| Join the group | 700 Cash + 6 Gems + x1 Item |
| Free Crate (invite 3 friends) | 4.50K Cash + 25 Gems |
Favouriting the game and joining the group are one-time claims that also drop a free item, so grab both on your first session.
Best early skills on the Skill Map
The Skill Map splits into a Cash branch and a Gems branch. The important rule sits in the tooltips: every Cash skill is lost on rebirth, while every Gem skill is kept on rebirth. That difference decides where each currency should go.
Cash skills to buy first
| Skill | Cost | Effect |
|---|---|---|
| Sharper Shots | 250 Cash | +15% Damage |
| Thick Skin | 250 Cash | +15% Health |
| Powder Load | 500 Cash | +25% Blast radius |
| Trigger Happy | 700 Cash | +15% Weapon speed |
| Lucky Shot | 850 Cash | +6% Crit chance |
Sharper Shots is the cheapest raw damage boost and the best opening buy, since faster kills mean faster runs and more income. Powder Load follows because a wider blast radius helps you clear the swarming groups that fill later waves. Lucky Shot is worth taking once cash is flowing, as extra crit chance quietly raises your damage across every fight.
Gem skills worth saving for
| Skill | Cost | Effect |
|---|---|---|
| Hard Light | 6 Gems | +20% Damage |
| Deep Plating | 6 Gems | +20% HP |
| Spotter | 10 Gems | Adds an in-fight zoom-out button |
| Scavenger | 14 Gems | +35% Pickup rate |
Higher-tier parts such as the Slugger, Cannon, Rail Gun, and Void are locked behind Rebirth 1 and Rebirth 2, so they only matter once you reset your progress for permanent power. Until then, keep your grid focused, claim every free reward, and let a reliable farm level fund each upgrade. That steady loop clears the Scrapyard far faster than panic-buying every part in the shop.
