OpenFront Combat — What Actually Kills Your Troops

Attacker losses are a ratio term plus a density term, and no amount of troops takes them below a factor of 0.6. Terrain then scales the result: plains 80, highland 100, mountain 120.

Every tile you take runs through the calculation below. Knowing it turns “should I attack?” from a feeling into arithmetic.

Terrain changes your losses

Lower ticks per tile is faster. Press Space for the terrain view and push toward plains first. The difference in ground covered per troop is large.

A “highlands 5.0” figure circulates in some writeups. That looks like the defense post multiplier (×5) mistaken for a terrain value. Terrain values are 80, 100 and 120, and they are magnitudes, not multipliers.

Multipliers stacked on top

⚠️ Bigger empires attack more efficiently. It runs against intuition, so it is easy to get backwards — but the formulas are explicit.

bonus = 1 − depth ÷ (1 + (300,000 / tiles)^2.5)
        depth: attacker 0.7 · defender 0.3

The same bonus multiplies both losses and advance cost. The attacker side uses your territory; the defender side uses theirs.

Territory (tiles)	When you attack (yours)	When you are hit (yours)
100,000	x0.96	x0.98
200,000	x0.81	x0.92
300,000	x0.65	x0.85
500,000	x0.45	x0.77
1,000,000	x0.33	x0.71

At 100k tiles it barely registers; between 200k and 300k it bends hard.

Attacking gets much cheaper as you grow; being attacked gets a little easier. The attacker depth (0.7) runs far deeper than the defender’s (0.3), so the net favours the big empire. When two large empires meet, both bonuses stack and the fight is cheap for both — the game’s aim is to keep late games moving, and the result is a snowball.

Your tile count is never shown on screen. Gauge it from the Owned % in the leaderboard — 300k tiles is roughly 46% on World Normal, about 13% on Europe Normal.

Losses are charged per tile, not per second

Getting this backwards throws off everything downstream.

Troops are not drained by the clock. They are charged each time you take a tile.

Two consequences:

• An attack with nothing left to take costs nothing. Sitting on a border is free
• A wider front does not reduce the loss per tile. What a wide front buys is speed

The advice to push on many fronts is right, but the reason is different: the per-tick advance budget scales with how many of your tiles touch the enemy, not with any loss discount. Taking the same 100 tiles costs the same whether you do it on one front or four — only the clock differs.

What actually lowers the cost per tile is how many troops you commit. That is the ratio term below.

Attack ratio

Attacker losses are the sum of two terms: a ratio term and a defender-density term.

The ratio term carries clamp(defender ÷ attacker, 0.6, 2.0). The floor of 0.6 is reached at attacker = 1.67 × defender, and losses stop improving there. Advance speed uses a separate clamp that maxes out at 1.22×.

The ratio clamp multiplies both terms. Sending more troops lowers your whole loss, but it stops at the floor of 0.6.

And because the clamp hits both terms equally, the balance between them does not depend on your troops at all. How much of your loss comes from density is set purely by how thickly the defender stacked.

This is where “pick thin targets” comes from. Troops buy you a factor of 0.6 and no more — below that, the only lever left is choosing a different target. Against someone spread thin the density term is under 1% of your loss; against someone stacked, it is nearly half.

→ Full breakdown in What Attack Ratio Should You Use?

Wilderness is a different formula

Unclaimed land is simpler. Loss per tile = terrain magnitude ÷ 5. Bots pay only ÷10.

• Plains 16 / Highland 20 / Mountain 24

The troop count at which advance speed maxes out differs by terrain: plains 6,600, highland 8,000, mountain 10,000. Beyond that, extra troops buy nothing.

Early-game optimization: overcommitting to wilderness gains no speed. Hold the ratio low (10–30%) and expand in several directions at once — advance rate scales with border length. The Opening Simulator plays this out against the real growth curve.

Encirclement — zero losses

Completely surround a player (so none of their tiles touch water or the map edge) and their territory is absorbed instantly with zero troop losses. Their accumulated gold transfers too.

Finding a small isolated bot and wrapping it is the strongest early move in the game. Scan your surroundings right after spawn and mark encircleable neighbors.

Retreating

The red ❌ in the event panel cancels an attack in progress. The cost is 25% of the attacking force.

Paying 25% to save 75% from a losing fight is usually correct. Troops are not consumables — they are your growth engine.

Retreating a boat sends it back to its origin; if that land has changed hands in the meantime, it attacks there instead. Nukes cannot be recalled.

Going around by boat

⚠️ Boats do not ignore defense posts. Several guides claim they do. The game creates a normal attack from the landing tile, and the defense post check looks at the tile being taken, not where the attack came from. Land next to a post and you eat the same ×5.

What boats actually give you:

• The landing tile itself is free — normal combat starts after that
• You can pick a coast with no defense post. That is what “going around” really means
• Up to 3 at once
• Sunk by a warship means total loss of the troops aboard — warship patrol range is 100 tiles
• Landing simultaneously with a ground attack splits the defense and helps a lot

→ See Defense Post Range and Placement.