A doc-style video to summarize early design and gameplay elements that were much more impressive compared to the final product. Infinite went through many revisions over the course of its development, Irrational Games had to scale back a lot of ideas, which was disappointing for a lot of people after the E3 showcases. Everything shown here has been removed or downgraded to the point where it's just not comparable. Self-explanatory quote from Ken Levine: "we cut enough content to make 5-6 full games". There's more in the official artbook if you're interrested.
----- Sources -----
Early Gameplay Demonstration /watch/YKmYAp-ti5ptY
E3 2011 Gameplay Demo /watch/8nx6bJYvttav6
About Sky-Lines /watch/UCFH_HgPYX4PH
Factions at War /watch/IOUhdBNa21mah
Windows Into Other Worlds /watch/cr09FCXFEbgF9
---- Key moments ----
0:01 City of Columbia
2:35 Tears
4:32 Sky-lines
6:13 E3 gameplay