While this could be the Shadow Isles before it's downfall, I don't believe this event portrayed in it IS the downfall, nor the possible subsequent actions(i.e. frantic hopes of resurrection). The Shadow Isles were once grand and cheerful as the tale describes, but the Shadow Isles were torn to pieces due to a civil war among its people. On top of this, the theory of the gambler being Twisted Fate is well thought out. After all, TF turned over his partner, Graves, when promised unrealistic magical talent. Graves was upset about this, and hunted TF down. Thus, this gambler was running and found the River King. It all fits so well. Except for it's blatant disposition in the timeline. The Shadow Isles were destroyed in civil war centuries before the current day in Runeterra, so the idea of TF, and possibly Eve, surviving that long is far fetched to say the least. But, let's suppose, the River King and his promise put some kind of voodoo magic on TF and Eve, making them somehow able to be in the present day. What about Graves and the governments of that time? They surely wouldn't have gotten that kind of voodoo magic that TF did, thus making the idea, however cool it seems, of TF being that gambler, highly unrealistic. I think that this was just an elaborate story line made by Riot to entertain us as well as tease at the next champion. In the end, this is most likely a cool story to give some background on the River King and his shady dealings, more or less giving us more personality to the champion.
Man that was a rant. I don't intend to sound mean or degrading, I just simply wanted to shed light on this rather shady subject and it's relation to the lore as its been presented.
