Learning League of Legends.
So, I keep trying to get my friends into playing League of Legends, because the lore is amazing (Thanks for that.) but no longer are you a summoner, and playing as a new player feels BAD. What is the purpose of a match? To win? Trying to win just to win creates this toxic idea of victory at any cost. You are no longer arbitrators for issues, or fighting for purpose.
Then learning how to play. The god aweful introduction. You are told you buy Thornmail on ASHE! (Really? Like, a short sword, a pickaxe, anything else?!) Then thrown into another match (Which has been improved slightly, but honestly, it is painful to play. ) Where you must pick between some ice arrow chick, a sword dude, or a weird mage. Then you get intro bots, which is a bit better but bots are dumb. Anyone who can game, blows past them. Anyone who can't struggles and doesn't understand why. (Children, young adults who have the chance to game for the first time, and older folks who are slow to change but enjoy what they see all play this game.) No one explains minions well, attack move commands, why objectives matter.
Even if you figure out how to destroy bots, it doesn't help against other players. Some get mad, some get annoyed, and some leave the game. We don't want more toxic players, we want to teach players and help them understand the game. We need a single player mode.
We need a chance for players to pick their favorite looking champion, play them, explore their abilities, buy items, and learn more about the game. People who play this game and know the basics want a sandbox mode for this same reason. You have a responsibility as a gaming company to bring in new players, and teach them about your game so they can play. So they can understand not just how to play, but why to play and who they can play. Then, allow them to purchase champions they are good at (Or during Free Week Rotation) for fighting other summoners to test their might.
Now with a roster of over 120 champions at 10 a week it takes 12 weeks or roughly 3 months of real life to make a full rotation. For a casual gamer, that means the champ you like the week you can play, you are unable to play for a week or two, you return to your limited pool (Which is static for the first few levels making it more confusing.) Learning to play a single champion can be a nightmare, let alone a single lane, or a single role. Not everyone can play a lot. That forces players to learn 'Simple' champions who are cheaper first, but they may not enjoy thematically. Trying to explain all this to a new player who enjoys how the game looks but who has never played a PVP game (Or even a MMO) is rough, but trying to let them learn via the built in system? Even worse.
Without new players, all games slowly fade and wither. While League might stay around for a very long time with its massive fan base, slowly it will dwindle and fade without new blood, and while people are coming, I see many people leaving too.
I personally believe the solution is already available in terms of Lore and story. Noxus training camps, untamed jungles with wild beast, lost temples fill with magical traps and constructs that battle with you. Doom bots showed you can create vortexs across the map, and dark matter rain. A temple you can explore with only Marksmen or a support training camp where you assist your team with a handful of threats. Deadly adventures you can only take your best Fighters on. Think your EZ is good enough to do the Tank mountain missions? Go for it, good luck.
Then, when people play across the missions as different champs, they can learn the roles of the champions, and how that creates a team. How to play, while enjoying the game. Players can forge connection to champions they love and understand. Then, allow them to take new forged connections and start to understand the lanes while knowing the characters they pick. Let them learn how a team is forged and what types of comps exist. Teach them where their favorite champion belongs, while preserving all the existing things they learned via playing alone and learning.
It doesn't need to be an offline mode. But it does need to be playable alone. Having paths and side missions that require a team, sounds amazing.
Now, with all that said, there are champions I love and would play single player, but I won't play PVP because I'm bad with them.
Learning new champions is rough. Some players watch pros, some read guides, some play them. There shouldn't be a wrong choice. There should be Riot guiding players on how they want the game played and learned.