King of Progress Build Guide: Lab Rat Upgrade Engine
A King of Progress build for 9 Kings 1.0: Lab Rat, Reinforce, Concabulator, and the upgrade loop that produces the highest-ceiling carry in the game.
Quick answer: The King of Progress build upgrades plots constantly and turns those upgrades into stats. Lab Rat gains a level whenever an adjacent plot is upgraded, Reinforce adds damage on every upgrade, and Concabulator upgrades the whole board. It is the highest-ceiling build in 9 Kings.
Progress is the upgrade king. Its cards care about plot levels, and its payoff is a carry that grows every time you improve the board. That makes it the most snowbally deck in the game: a good start compounds into an unstoppable board.
This guide covers the Lab Rat Upgrade engine, the upgrade loop, and the opening that gets you there.
The deck
Progress' nine cards:
- Mothership (base): a controllable flying base.
- Lab Rat (troop): gains a level when an adjacent plot is upgraded, with no cap.
- Executioner (troop): targets the lowest-health enemy.
- Defender (troop): does not attack; reflects all damage.
- Concabulator (building): at level 3, upgrades every plot by one.
- Reinforce (building): when any plot is upgraded, that unit gains +1% damage.
- Precision (enchantment): first hit always crits.
- Overhaul (building): destroys a plot to upgrade two random plots; each level adds one.
- Converter (building): turns an enemy into a rat that inherits tower stats.
The deck has one carry, three upgrade engines, and enough support to keep the loop running.
The Lab Rat engine
The core loop:
- Lab Rat on a plot adjacent to your upgrade targets.
- Reinforce on the board, giving damage for every upgrade.
- Concabulator upgrades the whole board at level 3.
- Overhaul sacrifices marginal plots to upgrade the important ones.
Lab Rat has no level cap. Every adjacent upgrade is a permanent level. In a long run, it can reach levels that no other unit can match.
The catch is that Lab Rat starts weak. You need the upgrade engine online before it becomes a carry.
Opening priorities
Years 1–3: take Lab Rat if it appears. If not, take Reinforce or Executioner. You need a carry before you need an engine.
Year 4: take Sharp Blades or Exploration. Sharp Blades helps the Lab Rat; Exploration gives you more plots to upgrade.
Years 5–7: place Reinforce next to the Lab Rat. Place your first upgrade target adjacent to the Lab Rat.
Years 8–11: save gold. Progress wants Concabulator at year 12.
Year 12: buy Concabulator if it appears. If not, buy a second Reinforce or an Overhaul.
The full board
By year 20:
- Base plot: Mothership.
- Carry plot: Lab Rat with Reinforce adjacent.
- Support plots: Concabulator and Overhaul.
- Front line: Defender and Executioner.
- Kill zone: Mothership and Executioner.
- Open plot: a second Reinforce or a Precision target.
Keep the Lab Rat next to the plots you upgrade most. Its levels come from adjacency, not from its own upgrades.
Decrees
The best decrees for Progress:
- Sharp Blades: +30% attack. The Lab Rat's damage scales with it.
- Exploration: extra plots. More upgrade targets.
- Feast: double max HP. Keeps the Lab Rat alive.
- Overwork: support buildings trigger one more time. Excellent with Reinforce.
Avoid Bunker. Progress is not a tower deck.
Perks
The Progress perks that matter:
- Innovator: +1 Reinforce card. More upgrade damage.
- Ranger: +20% Executioner damage. Good secondary damage.
- Admiral: +10% Mothership speed. More positioning control.
- Armored: +10% HP. Keeps the Lab Rat alive.
- Scientific: +10% upgrade effect.
Universal: Ingenious, Expansionist, Persistent, Nurturer, and Wrathful.
Upgrade order and Lab Rat caps
Lab Rat gains a level whenever an adjacent plot is upgraded, so the cheapest upgrades are the best ones. Upgrade a level-1 plot next to the rat before you upgrade a level-2 plot across the board. The rat does not care which plot you upgraded, only that the upgrade happened next to it.
Concabulator is the exception. Its level-3 effect upgrades every plot at once, which can give the rat several levels in a single year. Protect the Concabulator until it reaches level 3; a level-2 Concabulator is a support building, not a win condition.
Overhaul is best used on plots that have already produced their value. Destroy a Farm after the carry has scaled, or a support building you no longer need. Do not destroy the plots adjacent to the rat unless the replacement is already in hand.
If the rat is not adjacent to at least two upgrade targets by year 12, move it. A safe rat with no upgrades is worse than a risky rat with a real engine.
The Final Battle
Progress is one of the best Final Battle builds because the Lab Rat can outscale the boss. By year 33, it should have dozens of levels from adjacent upgrades.
The weakness is fragility. Lab Rat has low base HP. If the boss reaches it before it scales, the run ends. Defender and Feast are the insurance.
Common mistakes
Putting Lab Rat away from upgrades. Its levels come from adjacency. If it is not next to the plots you upgrade, it stays weak.
Upgrading random plots. Every upgrade should feed the Lab Rat or Reinforce. Do not upgrade a plot that does not contribute.
Skipping Concabulator. It is the biggest single upgrade in the deck.
Ignoring defense. Lab Rat is fragile. One Defender and one Feast can save the run.
The best cards→ page explains why Lab Rat has the highest ceiling, and the best builds→ page compares Progress with the other engines.
Before you upgrade a plot, check whether the Lab Rat is adjacent. If not, move the rat first.
FAQ
Is King of Progress good in 9 Kings? Yes. It is one of the two strongest kings in the 1.0 build, with the highest carry ceiling.
What is the best Progress build? Lab Rat Upgrade: Lab Rat, Reinforce, Concabulator, Overhaul.
Does Lab Rat have a level cap? No. It can keep gaining levels from adjacent upgrades.
How do I unlock King of Progress? Upgrade 299 plots across your runs.
Sources
Official source: 9 Kings Steam store page ↗