Sorry to burst your collective bubble, but it's extremely unlikely Yone will ever be a champion. Submit your downvotes and let them fall in a righteous downpour, but I'm going to give you five reasons why Yone _probably_ in't the "mystery" champion of the PROJECT. This isn't an attack on you if you think or thought it's Yone, but I've gotten tired of all the Yone speculation when everything points to otherwise. Again, this isn't to hate on you; I simply wish to shed a new light on the subject.
> 1) It'd Be A Poor Choice
First off, it'd be a poor choice on Riot's part to first showcase a champion with a skin first. Would we look at Tahm Kench the same way if he was first shown as a koi fish master chef, or easily connect Azir with Shurima and the desert if he first appeared as a spacefaring extraterrestrial? "This could be Yone's default appearance! It's happened before, like people getting Shuriman skins when Azir came out!" Okay, why would Yone be cybernetic at all? Dude's Ionian. Which brings me to my second point:
> 2) It Conflicts With Riot's Standards
They preach this time and again, when Riot makes a new character, they want to explore a new avenue of thought. Where would Yone fit into that ideal? If he wants vengeance, what'd differentiate him from Graves (pre-Burning Tides), another champion who wanted to enact vengeance on another? If he doesn't want vengeance but his memories are surpressed, what'd differentiate him from Sion? If his existence is torment, what separates him from Urgot? And if he's actually chill with being a cybernetic zombie, the hell am I looking at? I doubt Yone would be fine with that, and if his original personality isn't intact at all, what's the point of having Yone at all and not someone else who could have a story of their own? Just for the "drama" of having Yasuo face his brother again? Poor excuse. Even if Yone being resurrected as a cybernetic zombie story somehow got the green light, what'd differentiate him in-game from PROJECT Yasuo? They'd both be swordsmen with "Project" particles. Different abilities, sure, but similar stance and training. Would you honestly be fine with buying Yasuo all over again?
> 3) People Have Speculated Him Before
And probably will continue to. People have speculated Yone being added as a champion for a long time. Some people even thought he'd make it in way back when Yasuo was first teased, even though Yasuo freaking killed him.
It's an unfortunate reality, but too many people are too eager to mash their faintest dreams into something that clearly doesn't fit. Some theories are so wishy-washy, I lose faith in any credibility they could have. Like the "Seven Deadly Sins" theory, which fluctuates whenever a vaguely-malevolent champion has come out. Shadow Isles, the Void, Tahm Kench; none of those jive. And when people do try to localize the theory into something more buyable, they're forced to make ill-fitting choices. Why? Because they're trying to make something out of what isn't there.
> 4) He's Dead
Most importantly, the dude is dead. You might argue, "Well, it was never confirmed!" Yasuo buried Yone, it's written as plain as day in Yasuo's lore. "Well, maybe he lied about that!" Okay, if the third-person narrative is somehow unreliable, then for what reason would Yasuo lie about killing his own brother? And if he didn't kill his brother, why does he feel so irredeemable? "Well, maybe Yone was resurrected?" By whom, I ask you. "Someone from Piltover or Zaun, like Jayce or Viktor." Jayce raising someone from the dead is entirely out of character and illogical. Neither would Viktor have a reason to bring back some random Ionian dude from the dead. Why would he resurrect Yone, when he can easily convert the living and willing? And if he could raise the dead to build an army, why resurrect a single Ionian far from Zaun? "Well, maybe the Shadow Isles did it!" Okay, more believable. But why would Yone be a champion more than anyone the Isles would raise up? "Maybe Kalista would raise him up to enact vengeance on his brother." From what we've seen, Kalista makes deals with the living who have nothing else to live for, though nothing says Kalista _can't_ make a Pact with the dead. But if Kalista could raise up Yone from death, why doesn't she do that to every wronged person in the world? (Though again, nothings says that Kalista can't or hasn't already done that exact thing.)
> 5) There's Strong Evidence That It's Yi
This is the part of my argument that can be taken with a grain of salt. I have reasons to believe that it's Yi, but make of them as you will. Okay, in a recent update, all the colors and weapons of the PROJECT members were revealed. The topmost one and most ambiguous is a sort of golden-yellow, and the weapon showcased is some kind of blade. All the colors correspond to their respective champion; Yasuo orange (back when I think a color scheme wasn't established; he'd probably be blue were he made now), Lucian light orange (like the color of his blaster VFX), Leona sun yellow, Fiora pink, and Zed red. The golden-orange matches up best with Master Yi's effects, which are pretty gold-orange-yellow.
Alas though, the blade doesn't resemble Yi's sword. The blade IS named the Hyperlight "Alpha" Blade, like Yi's Q is named Alpha Strike, and the blade's specifications do say it's meant for "multi-target combat", which is exactly what Yi does when he Q's, but it doesn't resemble any blade of his. Lucian's pistols still look like his pistols, Leona's shield her shield, etc. The rest of the weapons are easily identifiable from their base form. That, I will admit, can't be refuted. The blade IS different from Yi's.
But that doesn't mean it can't be his. See, just because skins are part of the same line doesn't mean they're all the same price. Refer to Battlecast Skarner and Kog'Maw, two skins released at the same time but with different prices. Skarner got the more expensive of the two, but subsequently came with more stuff. He got a whole new voice-over as well as effects and model. Kog'Maw got the slightly cheaper one, not having a new VO. This shows that not all skins, even of the same line, are made equal. The same might just happen with PROJECT. Plus, Riot has made the topmost PROJECT candidate more ominous than the rest, saying things like "Trace lost" or "Data corrupted". They're hiding the "truth" that has appeared time and again in this skin-line tease. Based on prior experience with similar handling of upcoming content, this "mystery" should naturally be of a higher order than the rest. Put simply, you save the best for last, right? You don't spoil the biggest surprise, what has more gravitas, etc. And what'd have greater gravitas than a new Legendary skin, or, heavens forbid, Ultimate? (I doubt it being an Ultimate really)
We've already established that prices vary even in the same skin line at the same release. And since the sword is very different from Yi usually wields, that'd imply he'd need new animations to wield it properly. And people have been craving for a futuristic Master Yi skin for years (I argue Headhunter Yi is pretty rugged, too much so to qualify). Maybe you've seen the "Pulsefire Master Yi" fan-art that countless people have cried out for Riot to add in. What better way for Riot to realize that dream the fan base has conceived?
Now, one last piece of evidence before you go: The mysterious face that's tied with this whole PROJECT. It clearly has multiple "eyes", that much is abundantly clear. This has made some people to believe the champ is Jax, which I can't blame them for. The eyes closely resemble Headhunter Yi's eyes in their spacing, but it can be argued against. But here's something: The helmet has something going on with its top: A plume of sorts, similar to how PROJECT Yasuo's hair sticks out from beneath his helmet. If you look across all of Master Yi's skins, he usually has something going on with his helmet toward the back of his head. A plume wouldn't be out of the question, would you think?
Just food for thought.