Every ship and defense structure in pr0game relies on three primary stats (read more about it in Combat Values), all of which can be boosted by your research (Weapon, Shielding, and Armor tech add +10% to the base value per level):

1. Hull (Structural Integrity): The physical health of your ship. If this reaches 0, the ship is destroyed. Even if it doesn't reach 0, taking too much hull damage can cause the ship to explode prematurely (see Explosion Mechanics below).
2. Shield: An energy barrier that absorbs incoming damage before the hull is touched. Shields fully regenerate at the beginning of every round.
3. Firepower: The amount of raw damage a ship fires at its target.

Despite how fleets are grouped, the engine evaluates every single ship individually.
Here is the step-by-step lifecycle of a combat round:

Every ship alive at the start of the round gets to fire. Targeting is 100% random.

Simultaneous Firing: Technically, the combat system loops through ships sequentially (from left to right). However, because ships aren't completely removed from the battlefield until the end of the round, a ship that takes lethal damage in Round 1 will still get to fire its weapon in Round 1 before dying.

Before damage is dealt, the engine checks if the attacker's firepower is at least 1% of the target's total shield. If Attack < 1% of Shield: The shot completely bounces off. Zero damage is dealt, and the shield doesn't even dent.
Example: A Light Fighter firing at a Deathstar will bounce harmlessly off its massive shields.

If the shot doesn't bounce, it hits the shield.

If the shield is stronger than the attacj, the shield simply absorbs the damage, and its value is reduced for the rest of that specific round.

If the attack is stronger than the shield, the shield drops to 0, and the remaining damage penetrates and reduces the ship's Hull.

A ship does not need to hit 0 hull to be destroyed. If a ship's Hull drops below 70% of its maximum capacity, it becomes unstable and has a chance to explode on every subsequent hit it takes.
The probability of a ship exploding is exactly proportional to the damage it has taken. If a ship has 40% of its hull remaining, it has a 60% chance to explode upon being hit.

Certain ships have Rapid Fire against specific targets (e.g., Cruisers against Light Fighters). If a ship has Rapid Fire against the target it just hit, it rolls a weighted die. If successful, it gets to shoot again in that exact same round. This can chain multiple times until the Rapid Fire roll fails (read more about it in Rapid Fire wiki page).

Here is how you can optimize your fleet compositions:

Because targeting is 100% random, you can protect your expensive, high-damage ships (like Plasma Cannons, Battleships, or Destroyers) by flooding the battlefield with cheap units like Light Fighters or Espionage Probes. If the enemy fires a massive 3,000-damage shot, it is largely wasted if it randomly hits a 40-hull Espionage Probe.

When flying in an Alliance Combat System (ACS) attack, the game processes the fleets in the order they were added. Since the battle system processes shots from left to right:

• Send Heavy Ships First (Left): Have your Battleships and Battlecruisers arrive first in the ACS. They will fire first, smashing enemy shields with massive single hits.
• Send Light Ships Second (Right): Have your Light Fighters and Cruisers arrive in a slightly later ACS slot. By the time the battle system loops to them, the enemy's shields are already down. Their numerous, weaker shots will directly hit the exposed hulls, triggering the 70% explosion rule repeatedly.