Season 1 Buildings and the Resource Loop

What to build and upgrade first

Season buildings are temporary, but the Class EXP they help you earn is not. The useful order follows the unlocks, not a preference for spreading levels evenly.

1. Class Hall in the preparation phase. You cannot pick Engineer or War Leader, or spend Class EXP on season skills, until it is up. The professions guide covers the class choice.
2. Virus Lab as soon as you reach Base level 10. This is the resistance building, and resistance is what keeps the γ Pathogen off your marches. Push it early; Immune Protein spent here is doing the job the season is built around. Details of infection and storms are in the Radiated Land guide.
3. Uranium Crystal Refinery I next, and take it to level 5 before you worry about later ones. Refinery I unlocks when the Virus Lab is level 1. Refinery II unlocks only when Refinery I is level 5, III when II is level 10, and IV when III is level 10. Focus on the refinery that is currently unlocking the next slot, rather than levelling four incomplete buildings at once.
4. Then raise output on the refineries you have. Each goes to level 30 and lists Immune Protein per hour plus a max production time. The Season Weekly Pass adds one extra refinery; if you buy that pass, treat the extra slot as more Immune Protein for the Lab and for leftover conversion, not as a reason to neglect the Lab itself.

Radiation Shelter and the other season buildings below are worth placing, but they do not gate Virus Resistance or the refinery chain.

How the resource loop works

Uranium Crystal is refined into Immune Protein. Immune Protein upgrades the Virus Lab, which raises Virus Resistance. Leftover Immune Protein, Mutant Shards and Uranium Crystal become Class EXP at settlement. That is the whole loop: gather crystal, refine it, buy resistance, and bank what you do not spend.

Virus Lab

The Virus Lab goes to a maximum of level 30. It increases your troops’ Virus Resistance, shows your current Virus Resistance, and reduces soldier death rate while fighting γ Pathogen-infected zombies. It disappears after the season ends. You consume Immune Protein to upgrade it. It unlocks at Base level 10. Resistance, Immune Protein costs and upgrade times at each level are shown on the building in your city.

Uranium Crystal Refineries

Four personal refineries extract Immune Protein from Uranium Crystal. Each goes to a maximum of level 30, lists Immune Protein output per hour and a max production time, and is removed when the season ends.

Building	Unlock
Uranium Crystal Refinery I	Virus Lab level 1
Uranium Crystal Refinery II	Uranium Crystal Refinery I level 5
Uranium Crystal Refinery III	Uranium Crystal Refinery II level 10
Uranium Crystal Refinery IV	Uranium Crystal Refinery III level 10

Class Hall and other season buildings

Class Hall is the building you use to choose a class and class skills. It becomes available for construction in the season preparation phase.

Other Season 1 buildings:

• Radiation Shelter (max level 30) — a season defensive building, removed at season end.
• Weekly Pass Uranium Crystal Refinery — an extra refinery slot granted by the Season Weekly Pass, with the same role as the personal refineries.

What leftover resources become

When the season countdown ends, unused Immune Protein, Mutant Shards and Uranium Crystal convert to Class EXP and are sent by mail. The conversions are simple ratios:

Item	Conversion
Mutant Shard	1 Mutant Shard = 100 Class EXP
Immune Protein	10,000 Immune Protein = 100 Class EXP
Uranium Crystal	9,500 Uranium Crystal = 100 Class EXP

The 1,000 and 10,000 packs convert at the same rates. One Immune Protein (Warmup) item converts to 200 Class EXP.