Hello, this post is about a brilliant idea that I've had for some time now. Although I may not have been the first to have this idea nor the first to discuss it either, regardless I think it's worth getting to Riot's ear.
With LoL's infinitely evolving lore and backstory, I believe it'd be amazing if Riot were to make single-player (or multiplayer) campaign like instances of gameplay that are based on different parts of the lore. For example, there could be an instance for the Noxian invasion of Ionia, a great battle between Garen & Darius with their respective armies, an environmental issue involving countless Vastayan tribes, Ekko and his upbringing in Zaun along with his conundrum with Urgot, the famed battle between Zed and Shen or even Shen's father, Viktor and his so-called "Glorius Evolution", Yordles and their mystical way of life, something to do with Celestial characters such Aurelion Sol and Zoe, an encounter with Riven and Yasuo, etc. The possibilities are quite literally endless with LoL's vast lore and the creativity sewn into every fabric of the game. With the previously mentioned examples aside, Riot could not only just base instances on canon lore, but even on lore from skins such as the Blood Moon Saga or the Star Guardians. Riot could even incorporate instances to go along with future champion updates, such as when Kayle/Morgana get updated, a potential instance portraying the new lore could be included (for free or for sale).
Riot could do plenty more to incentivize buying instances than just awesome depictions of the lore, they could possibly add exclusive icons, wards, and even chromas to an extent that can only be attained through the purchase and playing of certain instances. Not only would this be an excellent way to portray certain events in LoL's history, but it would potentially be a phenomenal business move. Riot could sell instances in the LoL store for whatever price they deem fit, and I know for certain how much lore nerds of the game would love it. An instance can even be divided into editions or volumes such as "Ionian History Vol.1/2/3" or "Vastayan Tales Edition.1/2/3" and so on. Riot wouldn't have to make instances all that long, I think somewhere along the lines of 20-40 minutes of gameplay max would be more than enough. With Runeterra being the colossally story-rich world it is, the amount of creative potential for an idea such as this would act as something different for players rather than just the typical 5v5 PvP experience. I believe it'd also be a great alternative to Riot making an MMO as they're still to this day constantly writing and rewriting lore, especially with the continuous introduction of new champions such as Neeko. They'd be an easy yet awesome way to show off Riots creativity, artistic prowess, and skills as game developers to the community. The number of visuals and experimental environments that they could create are infinite.
The examples I've listed above are without a doubt a small fraction of what is possible with something like this, Riot could even introduce new mechanics into the game or finally bring about a smarter AI system that the game has been needing for the past 5 or so seasons. I hope you find this idea as mouth-watering as I do, from one lore nerd to another and thanks for reading.