Why Does Halo 5 uses Massive Space??

I was playing Halo 5 and i was thinking why would Halo 5 uses massive space, i have it on disc.but it still uses 25 GB space so it a mystery what could hide in the massive space. It could be the tons of ARMORY or just rare REQS. But please report beacuse im in a big mystery.

Probably just the large amount of textures and 3D models. Armor models don’t actually take up that much space. It would mainly be the environment (such as cliffs, water, etc.)