Games themselves aren't all that big to begin with, most of that data is from pre made maps, all that detail where everything is, yeah that costs a lot of storage.

Think of it of just having the building schematics of a shelf compared to having thousands of shelves pre build in some location. The schematics require a drawer to be stored, the thousands of shelves require an entire stockroom.

So how does this game function?, the game itself is just assets the game draws information from. The save files is where everything is stored. Most games have small save files, because the only thing they are, are just checklists what you have and what you don't. The save file in this game is all your data, the structures build, what has been explored world wise, what has been generated, items in chests, etc etc etc.

Pretty much the same as Minecraft, which is a perfect example, the game itself on my computer, with different save versions in it's directory, is like 630 mb in size. I had a save file, which was over 30 gigabytes in size, because of all the chunks i had loaded in, which all required it's own data from flying to the border of the world. I knew when i started, i knew when i stopped. That was 29 gigs of useless chunk information i could just erase.

Also known as... aka, the below.

Originally posted by deadshooter:

in two words - procedural generation