The Project Storyline.

In my opinion, the cyborgs we see fighting are in actuality model's created from the former champions we know. They have the deceased people's memories probably because either their brains were revived and used with the models or something else i couldn't possibly think of. I really wouldn't understand how else they have the memories.

The figure we see in Yi's memories must had been what killed him. Because he seems to be traumatized about it to the point where anything hostile is temporarily view as that creature. The background in his memories appears to be Ionia. This also must have been either decades or a century ago. Because they appear to be in a more futuristic timeline and I wouldn't say that's Piltover.

My theory is that a certain someone acknowledged these champions skills from the past and sought to make replicas. Reasons why vary. This man/woman could have created them to counter an enemy or destroy them. But their creations became aware of themselves and escape. Their master must have realized this and sent Project Zed to either contain or eliminate them. Or zed could just be hostile for some reason.

If you guys look closely in the beginning, you can see Project Leona's shield in the background. This must mean that she hasn't became aware of her self yet and didn't escape. Project Yasuo is confirmed to already be active but is // UNKNOWN. They must have a master that has the info and location on all them.

It is likely another video is to be shown. Yasuo and Leona have not been left out guys, only haven't been shown yet.