Tech Center Research — Season 2 (Polar Storm) + The Age of Oil
Season 2 in One Sentence
Season 2 — Polar Storm / Arctic Exclusion Zone — is a 48-day frozen map where temperature management (furnaces + Coal) is survival-critical, Titanium Alloy is the new material, and alliances are ranked by total Rare Soil accumulated. And it ends with the single biggest progression jump since T10: The Age of Oil, which finally lifts your HQ past 30.
Oil, Oil Wells and the Age of Oil tech tree are introduced at the end of Season 2 (the "Age of Oil" / Season 2 – Celebration phase). It needs Tech Center 30 plus part of the Special Forces research, and its final research lifts your HQ cap from 30 to 35. Core-tree node names are confirmed from our data; the temperature/Coal seasonal research is confirmed at the mechanic level (confirm exact node names in-game). New to the series? Start with Pre-Season and Season 1.
Season 2 Priority Order
1. Seasonal: temperature & Coal research (survival-critical)
The cold degrades your base if you ignore it. Prioritise the season's furnace / warmth / Coal-efficiency research the moment it opens — it keeps production, training and gathering running. Treat it as a gate: nothing else matters if your base is freezing.
2. Lean economy toward Rare Soil accumulation
Because S2 ranks by total Rare Soil accumulated (not territory held), sustained output wins. Finish any Economy nodes you skipped — the Output lines and the More Farmlands / Iron Mines / Gold Mines capacity unlocks. Remember you still have only two research labs until the Age of Oil arrives, so keep both busy.
3. Core combat: Type Mastery + Tactical Weapon + Hero
Keep converting to squad power: deepen your one Tank / Missile / Aircraft Mastery (Synergy → Damage → March Size → direct stats → Ultimate Defense, tier I then II), push Tactical Weapon (Support: Hero, Enhancement: Drone, Limit Break: Skill Star I/II), and continue your squad's Hero line.
4. End of Season 2 — THE AGE OF OIL (the big payoff)
When Polar Storm ends, the server enters the Age of Oil: oil becomes a new resource and your HQ can finally pass 30. Open the Age of Oil tech tree and work it in order — rush Fast Builder V + the 3rd Tech Center first:
- Unlock Oil Well — opens the oil economy
- Food Output V · Iron Output V · Coin Output V
- Oil Output I
- Fast Builder V · Research Enhancement V ← top-tier construction & research speed
- 3rd Tech Center ← a third research queue (huge throughput jump)
- Focused Training V · Rapid Field Dressing V
- Oil Output II
- Infirmary Expansion V · Emergency Capacity I
- More Oil Wells
- Training Cost I · Healing Cost II — cheaper troops and heals
- Parts Workshop ← a source of Drone Parts (the drone bottleneck)
- Oil Output III
- Base Expansion ← lifts your HQ cap past 30 (toward HQ 35)
Why: this single phase hands you elite build/research speed, a third lab that accelerates everything afterward, oil income, cheaper training/healing, a Drone Parts source, and the HQ 31–35 runway. It's the biggest jump since unlocking T10.
5. Cheap defensive picks
Round out Defense Fortifications (Extra Hospitals → Hold the Line / Counter Defense / Solid Defense) — sustain matters in a long attrition season.
What to Skip in Season 2
| Skip / defer | Reason |
|---|---|
| Intercity Truck | Minor payoff |
| Off-type Mastery / Hero lines | One squad type only |
➡️ Prev: Season 1 · Next: Season 3 — Golden Kingdom · Plan costs with the Research Calculator and Drone Skill Chips Calculator.