Factorio Forums

I always thought it was the number of artifacts the spawners dropped, but a few weeks ago I experimentally tested some theories.

Theory: Higher richness yields more artifacts from spawners
Biter spawners will always randomly drop between 2 and 10 alien artifacts, spitter spawners will drop between 5 and 15. These values are defined in demo-enemies.lua and enemies.lua and are independent of richness. In my tests very poor bases actually had slightly more (2-3%) artifacts then very good bases, but that's just down to randomness. When killing the same 40 bases on the same map seed, all settings the same except richness, the result was 366 artifacts for very good richness and 375 artifacts for very poor richness.

In the game files enemy bases have a richness_multiplier of 1 and a richness_base of 0 (multiplying by 1 does nothing, a base of 0 always gives 0 when multiplied with any number), whereas ores have 1500 and 500 and oil even higher numbers.

Theory: Higher richness means more dense bases
How close the spawners are (or how many there are) doesn't depend on the richness, you can easily test this by creating two new games with the same seed but different richness, you'll find no difference in spawner placement or amount.

Theory: It's the amount of aliens spawned
I have never heard the claim that it's the number of aliens that spawn from hives. The number of biters/spitters a spawner spawns depends on the pollution the spawner has absorbed, a list can be found here: https://wiki.factorio.com/Pollution#Native_life
The amount of pollution a spawner absorbs is also independent of other factors, it's 20 + 0.01 * [chunks pollution] every game second (60 ticks). The kind of biter/spitter the spawner sends out depends on the evolution factor.
I didn't test this experimentally as I just heard about this, but this seems very unlikely given the info above and people probably would have noticed if that was the case.

I have no idea if richness actually affects anything, every theory I tested so far seems to be false and the code I looked through also doesn't mention any changes depending on richness. I could think of two reasons why there is a richness dropdown for enemies:

• Mods can access these settings and make changes that depend on richness (although they would also be able to just enable the dropdown if required and keep it disabled for vanilla)
• In Factorio versions up to 0.6.4 (sometime 2013) the richness setting actually did something so they just left it in, or maybe forgot about it. It did what theory 2 above claims and created more dense bases: http://i.imgur.com/0eOKVfu.png