Pipe Dream: Singleplayer RPG map idea to unwind between PVP games.
This is something that crossed my mind in another thread relating to toxicity and frustration. One of the ideas to help alleviate frustration and reduce in some way the toxicity of League of Legends was a gamemode for players to have a power fantasy in League of Legends using the champions and gameplay they love, without the need to invest heavily into a game or have to deal with other players and a competitive attitude.
Much like how League of Legends was inspired by Warcraft 3's Defense of the Ancients: All Stars custom game, I took inspiration from Warcraft 3: The Frozen Throne's Horde Campaign where you travel the lands in an RPG setting using the same mechanics as the RTS game, fighting off monsters and completing quests similar to Diablo and custom RPG games of the time.
While I highly doubt Riot is currently willing to invest the time and money into a new gamemode like this that isn't team focused in League of Legends, it is at the very least fun to imagine and may inspire Riot on future games.
Perhaps if Riot implemented a singleplayer mode where a player can play at their own pace without any other players on the enemy or their own team, it could give them a place where they can unwind and not worry about other players and just enjoy a power fantasy. Even in Co-op vs AI, a player who just wants to win to grind IP can effectively ruin a game for a person who just wants to putz around with their favorite champion, which is why I don't think Co-op vs AI is enough to address this.
This would be quite a long shot, but perhaps something like the Warcraft 3: The Frozen Throne's Horde RPG campaign would be a great way to enjoy the game and champions without forcing you into a competitive environment. The problem with this idea is that it would take quite a bit of work from Riot to design the map and quests for the player to do. The up sides for development is that aside from bug testing, there would no need for balance changes for this mode, or item modification and additions, and text/dialog could be generic enough for any champion to be used, which would reduce development overhead.
I do foresee several champions having trouble in such an environment, but I can also see them getting around it somewhat and provides a challenge that a player can try and overcome through rapid iteration instead of trying to re-queue for another game which takes much longer. Mark of the Ninja is very good at this as you are not punished very much for death and can very quickly return to the place you died to try again in a different way without much hassle and not get frustrated.