Damage

Damage Types

Damage type	Used by
Physical	Bullets (regular/piercing), shotgun (regular/piercing), biters, axe (iron/steel), collision (of train/car)
Fire	Flamethrower
Acid	Worm Turrets
Poison	Poison capsule
Explosion	Rockets, Explosive Rockets
Laser	Laser turrets, distraction/destroyer robots, personal laser defense

Resistance

Resistance has two aspects:

Percentual resistance

Is applied first and will just reduce the damage by the specified amount of percent. If the percentage is 100%, the entity is immune to the damage.

Decrease resistance

It decreases the damage by specified number as long as the result damage wouldn't be less than zero. When the result damage would get less than 0, the extra resistance is used as denominator in the fraction of damage that is going to be dealt

Formulas

Decrease < Damage

Result damage = (Damage - Decrease) * (1 - Percentage)

Decrease >= Damage

Result damage = 1 / (2 + Decrease - Damage) * (1 - Percentage)

Damage	Resistance	Result damage
5	0	5
5	1	4
5	2	3
5	3	2
5	4	1
5	5	1/2
5	6	1/3
5	7	1/4
5	8	1/5
...	...	...