>>714664351
You start the game and its those 3 biomes (jungle where you crashed, desert/mountain climb, city).
After that you have a big ass cutscene that has a really neat moment on it and you open a second "run" which has 3 new biomes. You finish that run to finish the story and open the chance to do the "real ending".
You can run either "half" when you want but they are just 3 biomes each, you can't run the 6 on a single run