OpenFront Terrain Guide
Terrain is the game's built-in defensive multiplier. The same attack, the same army, a different price — purely because of the ground.
Quick answer: every land attack is priced by the terrain it crosses. Plains are the cheapest ground, highlands cost more, mountains cost the most, and impassable terrain cannot be attacked at all. A defence post multiplies the defender's advantage on top of that.
Terrain cost table
| Terrain | Attack loss factor | Advance cost | Compared with plains |
|---|---|---|---|
| Plains | 80 | 16.5 | Baseline — the cheapest ground to fight over |
| Highland | 100 | 20 | About 25% more expensive |
| Mountain | 120 | 25 | About 50% more expensive |
| Impassable | — | — | Cannot be attacked — treat it as a wall, not a route |
What the numbers mean in play
- Plains into plains is the cheapest war — and the most common mistake is fighting somewhere else.
- Mountains are defence you did not pay for — a mountainous border needs fewer defence posts because the terrain already multiplies your effective defence.
- Highlands are the quiet tax — a quarter more expensive will not stop an attack, but it makes long pushes unprofitable.
- Impassable terrain changes strategy, not just cost — v0.33 added impassable ground, which created new chokepoints and closed old routes.
Terrain plus defence posts
A defence post inside its 30-tile radius multiplies the defender's effectiveness (a 5× loss factor in the live build) and slows the attacker. Stacked on mountains, that is why experienced players ignore the strongest-looking border and find somewhere else to fight. Buildings reference
Terrain plus fallout
Nuclear strikes leave fallout that reduces the defence modifier from 5× toward 2.5× as the fallout ratio rises. Nuked ground is therefore cheaper to push through — one of the few ways to make a defended mountain attack viable again. Treat the exact values as patch-sensitive; nuclear behaviour was adjusted in the v0.33 line.
Using terrain deliberately
- Anchor your defence on terrain — mountains and coast are free walls; put your defence posts where terrain does not help.
- Choose your attack axis by terrain — the same war costs half again as much across a mountain range.
- Use impassable ground to close routes — if a wall exists, you have one fewer front to watch.
- Re-check after map changes — new maps and terrain rules move the walls; a route that worked last patch may be closed.
FAQ
Common questions about this topic.
Which terrain is best to attack across?
Plains. Mountains cost about 50% more than plains to cross, and highlands about 25% more.
What is impassable terrain?
Ground that cannot be attacked or crossed. The v0.33 line introduced impassable terrain on maps, creating new chokepoints.
Do defence posts matter on mountains?
They stack with the terrain multiplier, which is why a defended mountain border is usually a losing attack — find a cheaper axis instead.
Does terrain change during a match?
The map's terrain does not move, but fallout after nuclear strikes changes the defence modifier on affected ground.