(Taken from the post; i did not make this)

Hey hey!

I thought it was time I gave you an update on the world generator changes we’ve been working on. The last time we did any major changes to the generator was back in March 2012, when the jungle biome was added.

In case you don’t know what a “biome” is, it’s a climate zone used in the game to set what kind of surface the ground has (sand? grass?), whether it should rain or snow, what trees grow there, and sometimes also what kind of animals that are allowed to spawn there. The biome is also used to determine how hilly it should be, although this is a technical solution because biomes are generated before the elevation (the old generator created the elevation first, and decided on biomes based on elevation).

One reason why we rarely do changes to the world generator is because every little change off-sets the world seed and causes noticeable borders between new and old terrain. A lot of people don’t mind about these borders, but we still want to avoid creating them. So, in order to avoid needing to change the world generator again in the nearest future, we try to do as many changes now as possible.

There have been three main problems we have wanted to address:

-Too large oceans
-Too uneven/random biome placement
-Not enough variation
-The solution to these problems have been,

-Tweaks to add more islands and checks to avoid huge oceans
-Biomes have been put into four main categories: snow-covered, cold, medium, and dry/warm. -Biomes will avoid getting placed next to a biome that is too different to itself (sometimes this still happens, but it’s very rare now and not all over the place)
-We’ve added a whole bunch of new biomes…
… and most biomes have uncommon/rare variations that you may run into
-We’ve also added a bunch of new terrain features, such as new flowers and trees

We’re not done yet, but here’s something to give you an idea of what has happened

 1.6 Biome Map


 1.7 Biome Map