OpenFront Buildings
Costs, build times and what each structure actually unlocks — a reference table first, then the decision behind each build.
Quick answer: cities raise your troop ceiling, factories and ports produce gold through trade, defence posts multiply the defence of a border segment, and silos, SAMs and warships are endgame tools. Costs rise as you own more of the same building, with hard caps.
Cost and effect table
| Building | Cost (live build) | Build time | What it does |
|---|---|---|---|
| City | min(1,000,000, 125,000 × 2ⁿ) | 2 s | +250,000 maximum troops per level; upgradable |
| Factory | min(1,000,000, 125,000 × 2ⁿ) | 2 s | Spawns trains that earn gold while travelling; upgradable |
| Port | min(1,000,000, 125,000 × 2ⁿ) | 5 s | Spawns trade ships; naval coverage; upgradable |
| Defence Post | min(250,000, 50,000 × (n+1)) | 5 s | Within 30 tiles: 5× defence for the owner, slower attacker advance |
| Missile Silo | 1,000,000 | 10 s | Launches atomic and hydrogen bombs; 9 s cooldown per silo |
| SAM Launcher | min(3,000,000, 1,500,000 × (n+1)) | 30 s | Intercepts incoming missiles in range; 9 s cooldown |
| Warship | min(1,000,000, 250,000 × (n+1)) | — | Naval unit; shells deal 250 damage and live 2 s in flight |
Weapons and ammunition costs
| Item | Cost (live build) | Notes |
|---|---|---|
| Atomic bomb | 750,000 | Blast: 12-tile inner radius, 30-tile outer radius |
| Hydrogen bomb | 5,000,000 | Blast: 80-tile inner radius, 100-tile outer radius |
| MIRV | 25,000,000 + 15,000,000 × missiles already launched | Splits into warheads (12/18-tile radii); price escalates per use |
City, port, factory: what each one is for
- City — a military investment. It does not produce gold; it raises the ceiling that limits how large an army you can hold. Build it when your army is capped.
- Factory — an income investment for inland positions: trains travel through cities and pay out based on the cities they visit.
- Port — an income and naval investment for coastal positions: trade ships pay more over longer routes, and ports are the base for warships and sea invasions.
- Defence post — a border investment. It is the cheapest way to make a specific border unattractive, and worthless on a border you do not have.
How repeat costs change your decisions
Because city, factory and port costs double with each copy (until the 1,000,000 cap), the useful question is never 'should I build another one' but 'is this the cheapest way to raise my ceiling or my income right now'. A tenth city is often several times the price of a first defence post on the border that is actually being attacked. Building timing turns this into an order of operations.
FAQ
Common questions about this topic.
What is the best building in OpenFront?
There is no universal best: cities raise your troop ceiling, ports and factories produce gold, and defence posts protect a specific border. The value of each depends on what your position is short of.
How much does a city cost?
min(1,000,000, 125,000 × 2ⁿ), where n is how many cities you already own — 125,000 for the first, doubling up to a one-million cap.
How long does a building take to finish?
Cities and factories 2 seconds, ports and defence posts 5 seconds, missile silos 10 seconds, SAM launchers 30 seconds, at a 100 ms tick rate. Instant-build lobbies change this.
Do defence posts stack?
Each post covers a 30-tile radius and multiplies defence inside it. Overlapping posts are usually unnecessary; spacing them along a real border is the efficient use.