The bug :

There is no difference beetween Giant Spruce Taiga Biome and Giant Spruce Taiga Hills Biome. The supposed hillier version is not. The problem is that the game isn't using correct values of setBaseHeight and setHeightVariation when generating the Giant Spruce Taiga Hills (Giant Spruce Taiga and Giant Spruce Taiga Hills are using the same values).

This bug exists since these biomes were added in the game, in 1.7.2.

It is not a feature suggestion, because it is clearly not intended. These biomes are coded exactly identical, only their name changes. Don't tell me that developpers intentionally added a "Hills" variant which is generating exactly like the non-Hill variant.

How to reproduce :

-Create a buffet world for each biome, and see that there is no difference beetween the two variants.

-Or create a new world with the seed : 3743090988927099363

Go at coordinates 0 ~ -2180. There is a river, with a Giant Spruce Taiga Hills on the north side and a Giant Spruce Taiga on the south side. You can see that there is no terrain's difference beetween them, Giant Spruce Taiga Hills isn't hillier.

 

Giant Spruce Taiga :

 

 

Giant Spruce Taiga Hills :

 

 

Relief difference : 0

 

 

If you're thinking it is a feature suggestion, see the code. There is differences beetween Giant Tree Taiga and Giant Tree Taiga Hills for example, but no difference at all beetween Giant Spruce Taiga and Giant Spruce Taiga Hills.

 

Source code of Giant Spruce Taiga and Giant Spruce Taiga Hills :

 

 

Comparison with source code of Giant Tree Taiga and Giant Tree Taiga Hills, which work as intended :

 

Exact location of the code + all the source code of these 2 biomes :

Location of Biome list :

.minecraft\versions\18w49a\18w49a.jar\bbv.class

We can see on this screenshot that "giant_spruce_taiga" is using the bcv.class file, and that "giant_spruce_taiga_hills" is using the bcw.class file.

We will comparate them to "giant_tree_taiga" and "giant_tree_taiga_hills" after, which use respectively bcx.class file and bcy.class file.

 

 

Location of Giant Spruce Taiga Biome code :

.minecraft\versions\18w49a\18w49a.jar\bcv.class

 

 

 

  

 

 

 

Location of Giant Spruce Taiga Hills Biome code :

.minecraft\versions\18w49a\18w49a.jar\bcw.class

 

We also can see that everything is exactly the same. The Giant Spruce Taiga Hills Biome will not generate as intended, there won't be any difference with the Giant Spruce Taiga Biome.

(You maybe noticed l.49, and thought that they were the wrong files. However, as we can see in the bbv.class.file, these bcv.class and bcw.class files are the ones used by Giant Spruce Biomes. I would guess that they use a part of Giant Tree Biomes files, which explains l.49)

 

 

Comparison with bcx.class and bcy.class (used by Giant Tree Taiga biomes) :

 

 

 

Here, the setBaseHeight value and the setHeightVariation value are correct. The Giant Tree Taiga Hills will generate as intended.

 

Edit (1.14.4 Pre-Release 1) :

In 1.14.4 Pre-Release 1, files names were changed (location is the same) :

• biomes are now listed in .minecraft\versions\1.14.4-pre1\1.14.4-pre1.jar\biq.class
• Giant Spruce Taiga Biome now uses .minecraft\versions\1.14.4-pre1\1.14.4-pre1.jar\bjq.class
• Giant Spruce Taiga Hills Biome now uses .minecraft\versions\1.14.4-pre1\1.14.4-pre1.jar\bjr.class
• Giant Tree Taiga Biome now uses .minecraft\versions\1.14.4-pre1\1.14.4-pre1.jar\bjs.class
• Giant Tree Taiga Hills Biome now uses .minecraft\versions\1.14.4-pre1\1.14.4-pre1.jar\bjt.class
• nothing else than locations changed, this is why I didn't update screenshots (that were taken in 18w49a)

How to fix the bug :

In the Giant Spruce Taiga Hills line code, change the value of setBaseHeight from 0.2F to 0.45F, and change the value of setHeightVariation from 0.2F to 0.45F

This won't change the global world generation, but only the way this specific biome is generated (and this biome is rare so it will not cause any issue of bad world generation caused by updating from an older version).

There is like 2 numbers to change, which will make more variety in Minecraft, as it was intended in the first place by creating Giant Spruce Taiga Hills in 1.7.2

I hope it will get fix as soon as possible, there is really not much to do in order to fix this bug !