Evolution/ru

Evolution

The game evolution factor is a global variable that determines what kind of biters will be spawned. You can check the variable in the dev console:

game.player.print(game.evolution_factor)

It goes from 0 (not evolved at all) to 1 (maximal evolution). At the moment the evolution factor can only increase. This evolution factor is increased by three kinds of events:

• The passage of time very slightly increases the evolution factor.
• The global Pollution Production increases the evolution factor.
• Destroying the enemy spawners significantly increases the evolution factor.

All these values are set in game.map_settings. There they can also be changed / modded.

Current (0.12.4) default settings are:

-- percentual increase in the evolution factor per tick.
game.player.print(game.map_settings.enemy_evolution.time_factor

0.000004

-- percentual increase in the evolution factor for 1000 Pollution Units
game.player.print(game.map_settings.enemy_evolution.pollution_factor)

0.000015

-- percentual increase in the evolution factor for every destroyed enemy spawner
game.player.print(game.map_settings.enemy_evolution.destroy_factor)

0.002

Pollution production is the total pollution produced by buildings per tick, not the pollution spreading on the map, so it is not reduced by trees or other absorbers. e.g. : 15 burner mining drills produce 150 pollution per second, raising the evolution factor by 0,00000225 per tick.

The percentages are applied on the base of (1 - current_evolution_factor). So for instance destroying the enemy spawner in the beginning of the game results in increase of evolution factor by 0.005 (half a percent) while doing this when the evolution factor is 0.5 the increase is only 0.0025 (quarter a percent).

As of 0.9.1 the biter spawning is done probabilistically based on the current evolution. Lets imagine a wheel - the "spawning wheel". We will be slicing that wheel as a cake. Small biters take the first 0.3 part of the wheel, medium ones the middle 0.3 part and big biters take the last 0.4. When a biter is about to be spawned the random point on the wheel is selected limited by the current evolution. So in theory while the evolution is below 0.3 there should be only small biters, then slowly medium ones will enter and in the end the big ones. The composition of the biter animation in the end should be 0.3-0.3-0.4. There is one more factor called the spawn_shift - this is a mechanism when the further away from the starting location the more the "rolling of the wheel" is shifted towards one. That means that if the shift is 0.2 for instance that at the time when evolution factor is 0.25 the result for spawning is actually 0.2 + 0.25 = 0.45 and a medium biter might be spawned.

Besides choosing what kind of biter will be spawned the evolution also influences the spawning interval. As of 0.9.1 this interval (spawning_cooldown in the enemy-spawner definition) is interpolated between 360 (0 evolution) and 150 (1 evolution) ticks.

All the values for the spawner (distribution of the biters based on evolution, the spawning shift, spawning_cooldown, etc.) can be modded from the data.

Spawn chances by evolution factor

	Biter's Nest
Factor	Small Biter	Medium Biter	Big Biter	Behemoth Biter
0	100.0%
0.05	100.0%
0.1	100.0%
0.15	100.0%
0.2	100.0%
0.25	100.0%
0.3	100.0%
0.35	75.0%	25.0%
0.4	56.3%	43.8%
0.45	41.7%	58.3%
0.5	30.0%	70.0%
0.55	20.5%	79.5%
0.6	12.5%	87.5%
0.65	6.7%	77.8%	15.6%
0.7		66.7%	33.3%
0.75		50.0%	50.0%
0.8		33.3%	66.7%
0.85		28.6%	71.4%
0.9		25.0%	75.0%
0.95		22.2%	77.8%
1		12.5%	50.0%	37.5%

	Spitter's Nest
Factor	Small Biter	Small Spitter	Medium Spitter	Big Spitter	Behemoth Spitter
0	100.0%
0.05	100.0%
0.1	100.0%
0.15	100.0%
0.2	100.0%
0.25	100.0%
0.3	41.7%	58.3%
0.35		100.0%
0.4		100.0%
0.45		100.0%
0.5		100.0%
0.55		75.0%	25.0%
0.6		50.0%	50.0%
0.65		21.4%	64.3%	14.3%
0.7			75.0%	25.0%
0.75			62.5%	37.5%
0.8			50.0%	50.0%
0.85			37.5%	62.5%
0.9			25.0%	75.0%
0.95			22.2%	77.8%
1			12.5%	50.0%	37.5%