After completing “Entangled” and “Final Glimpses,” you’ll then be on the home straight. All that’s left are two main quests: 

• Revelation
• One Giant Leap

“Revelation” is the big final mission, while “One Giant Leap” is the cutscene finale, effectively. AKA Decision time. Simply complete “One Giant Leap” and this achievement is yours, regardless of what you decide.

It is worth noting, though, that one choice in “One Giant Leap” will send you back into the universe you’re in, while the other, does not. So, get everything you want to get done before this point, or prepare a save beforehand, so you can get back to what you were doing regardless of your choice (which is exactly what we did).