This is with OldGroupRarity: false

Could it be something to do with OceanBiomeSize?

Either way, there needs to be a way to completely disable oceans.

I will point out where you got this from was a Spigot server so this might just be a problem on Spigot but we'll have to do additional testing.

Nah it also happens on Forge, we've known about it for a while

I remember when this was happening to me, it was because under the default ocean biomes, I was referring to biomes that didn't actually exist in my preset (because I had copied over the Default world config to start editing, but never copied over the Ocean biome). Removing the references and leaving them blank didn't fix it, I had to actually move the biomes over into my preset. Presumably I could have also just referenced existing biomes that were already in my preset, but this seemed cleaner.

Should check this out for 0.1.0 to make sure biome groups are working properly, and also document the way new biome groups work.

Fixed LandRarity and OceanBiomeSize for 0.0.18, if there are still problems, feel free to reopen this issue.

For 0.0.18 LandRarity 1-100 now work ok, but LandRarity 0 changes biome layout and still does not spawn oceans only.

For 0.0.18 LandRarity 1-100 now work ok, but LandRarity 0 changes biome layout and still does not spawn oceans only.

Wait, is that what LandRarity 100 is supposed to look like? I thought it was meant to have no oceans. Unless those are large lakes.

For 0.0.18 LandRarity 1-100 now work ok, but LandRarity 0 changes biome layout and still does not spawn oceans only.

Wait, is that what LandRarity 100 is supposed to look like? I thought it was meant to have no oceans. Unless those are large lakes.

Those arent oceans, it's just the biomes going below sea level.

We've decided not to fix this.

We will not be fixing the biome layout issue for this release, but still need to fix the landrarity 0 issue.

The landrarity 0 issue is fixed two ways by 0fd4c9d

landrarity 0 now doesn't spawn any land
also added a setting ForceLandAtSpawn, which can be disabled to avoid forcing land around 0,0