OpenFront Buildings

OpenFront has six structures: City, Port, Factory, Defense Post, Missile Silo, and SAM Launcher. A button lighting up is not a reason to click it. Ask what problem you have right now: troop cap full, no gold, a repeating land approach, no sea income, a nuclear threat, or a nuclear target. Then buy the matching building. Hotkeys are on Controls; this page is timing and placement.

First-match order is still City then Port, as in Getting Started. Everything below assumes you can already spawn and not dump the army.

City

Cost uses min(1,000,000, 2^n × 125,000): 125k → 250k → 500k → 1M, then capped. Each level adds 250,000 troop cap. Build time is about 20 ticks. Cities can stack and upgrade, and they do not need a Port first. They also act as train stations.

Build a City when the troop bar keeps slamming the ceiling on a quiet border. Do not build one as a panic button after you just emptied the army; the cap is not the problem, the missing troops are. Inland is fine. Put it behind the front so a raid does not delete the cap you just paid for. After three or four levels, upgrading an existing City is usually better than scattering a fifth new footprint for SAM to cover.

The Complete And Current Openfront IO Tutorial From An Expert

Port versus Factory: the shared cost counter

Port and Factory share PortBuildableGroup. The first of either is 125,000; the next is 250,000, then 500,000, then 1,000,000, regardless of which type you picked. Buying a Factory first makes the first Port expensive. Buying two Ports first makes the first Factory expensive. Plan the pair, not the icon.

Port (about 50 ticks to build) is the naval hub: trade ships, transports, and warships. You need a Port on that water to spawn warships there. Higher Port level improves trade spawn rate and revenue. Capture transfers the Port to the new owner. Build a Port when a connected sea has a trade partner, or when you must control a landing. Skip it when the only water is a puddle with no foreign Port and no invasion threat. Full ship play is on Naval.

Factory (about 20 ticks) spawns trains. It needs a City or Port within about 110 tiles, and rail segments have a limit around 155 tiles. Train spawn rate scales with factory count: (factories + 10) × 15 ticks as a rate parameter. Trains pay gold at stations: about 10,000 at your own City, more at ally or foreign stops (community figures: 25,000 other-player, 35,000 ally, before stop penalties). A Factory beside empty land with no station in range is a moving train that never cashes. Build it when the core is safe and a City or Port already exists as a stop. Do not build it to “have industry” on a burning front. Full rail loops, v0.33.12 spawn fixes, and skip rules: Trains.

Defense Post

First post 50,000, then 100k / 150k / 200k / 250k cap (min(250,000, (n+1) × 50,000)). About 50 ticks. Cannot stack on the same idea as City levels: each post is a separate tower. Range is about 30 tiles, with mag ×5 and speed ×3 for defender-owned land in the zone. Destroyed on capture — it does not transfer. That is the opposite of Silos and SAMs, which can change hands with the tile.

Place a post on a neck, mountain pass, rail entrance, or the one plains approach people actually use. Do not drop it in the geometric center of a blob that nobody attacks. A second post on a second approach beats two posts on the same tile you already own. If the front will move in the next minute, save the gold; a captured tile deletes the building.

Missile Silo and SAM

Silo is a flat 1,000,000 each, about 100 ticks, no cost scaling. It does not include a free nuke. Atom 750,000, Hydrogen 5,000,000, MIRV 25,000,000 + 15,000,000 × launched count. If you cannot afford the Silo and the first Atom (1.75 million together), you are planting a target. Upgrades shorten reload. v33 puts the Silo on cooldown after a MIRV. Details and SAM nets are on Nukes.

SAM starts at 1,500,000, then 3,000,000. About 300 ticks. Range grows from about 70 to 150 tiles by level. Cooldown about 90 ticks. In v33, in-flight MIRV warheads are interceptable; the MIRV carrier is not. SAMs do not cover allies. Cluster enough to overlap cores, not so tight that one Hydrogen deletes the whole net.

A practical buy order (not a religion)

Quiet FFA land map: City → Port (if there is a sea) → Defense Post on the real neck → second City → Factory once a station exists → Silo only with ammo money → SAM when a silo you cannot ignore appears. Island map: Port earlier, Factory later, warships before a pretty rail. Team backline: extra Cities and a Factory so you can donate; see Team Games. Diplomacy does not replace a post on the border you just opened; Alliances is a timer.

Win condition is still ~80% of non-fallout land (How to Play). Buildings help you hold and fund that land. They are not the win. The Guides Hub links every tutorial. The Tier List Hub is a short meta take after you know these costs. The Updates Hub is for patches that change a formula.

Buy late, not lonely. A City with no reserve, a Port with no warship gold, a Factory with no station, a post on a moving front, a Silo with no Atom, or a SAM with no threat are six ways to donate gold to the player who attacks next. Name the problem, spend once, then look at the troop bar before you arm another structure.