What makes an action fun

 From playing Borderlands 2 again something hit me when playing Maya. The characters mostly chosen/ played in games aren't the powerful characters, not really I'd say but rather the more diverse build characters.

What do I mean by this? A character that allows for a wider arrange of skill expression. The wider the skill expression such as the changes to Symetra in Overwatch 2 opened her from more niche players to a wider player base with turning her from her more defense heavy play style origin to her more active aggressor role defense side or offense side now along with mobility.

So it stands to reason in other games that the other more chosen than not characters are more fun related. That and with nerfing said fun the characters that are dropped are the ones where doing something powerful too easy no one wants to play them as well even if they do allow for a diverse skill expression. However, why?

Simple; the average player wants a character that can fill different roles but is specialized to one role. Someone like Beyonetta in Smash 4 is dull, not fun, etc. She has a wide arrange of ways to play her but little to no specialization along with little to no reward when playing her.

An action ability can be broken down into these parts.

Uses

This can be from things like using Widowmaker's grappling hook for aggressive mobility or defensive mobility. The use cases as of how and in what way you can use it. These are a question of use case A, B and C; too many use cases of making it useful and it's boring unless it has a big pay off/ big cost.

Interaction

This is a question as of how does it change how you interact with other things within the game world. It could be the following; how does A affect B. Let's say I have an enemy that I phase lock with Maya, doing so with her Helios ability active while she is at level 11, her interaction is turning the bandit into an AoE.

The interaction changes how you use the phase lock in question. It locks a target in place and having it where said ability changes the interaction.

A different example; using the anvil in minecraft with the enchanting books, you have a interaction of A being able to apply to B.

Again too many ways of interacting/ affecting other things within the game like Steve from Minecraft for Smash 5 you have a character that's boring, lackluster and overpowered along with overwhelming the players and changing the combat up too much.

Path of Exile has my favorite example of doing this idea correctly; the Ego skill that turns an AoE benefit to a single target self benefit of selfishness with only helping yourself. A change of interaction from a team player to someone selfish and self reliant.

The more complex the game is, the more you can afford to have many different styles/ ways of interacting.

Level of effectiveness

The level of effectiveness can change how an item is viewed; it doesn't matter how many niche cases it has for uses (unless it's oil from DnD) the question being; does it have enough effectiveness in what it's supposed to do?

Reaction

How does things react in the world/ the game in question? Do enemies run away when you have a specific gem equipped, does your skill gem give you shock immunity. How does it cause the game world to react.

There are under the surface mechanics/ systems that you can find yes but I'm talking about surface level. I am speaking of what you can clearly see happen within the world/ game. In Zelda BotW you can completely solve puzzles in ways they weren't meant to be solved, you have many different reactions from the game world with what you try to do and not do.

The game world is effectively responding to your action.