You know, sometimes a game can be really complicated. This can range from a complex, but fulfilling challenge to needlessly cumbersome. At any point on the spectrum, a game can become inaccessible to a larger audience due to its complexity. To some, this is the fault of the game; to others, the fault of the gamer. But either way, some games are just overwhelmingly complex.
The first example I can think of is Disgaea, a series of strategy RPGs that utilize over-the-top cartoonish (more technically anime-ish) characters and dilemmas to frame a highly customizable battle system.
In a Disgaea game, you have several different units, all differing in stat distribution, skills, movement, potential, and more. Many of these units are player-created, and can be reincarnated as different classes (or back into the same class) later on, causing quite a variety of skill sets. They can also become level 9999, and you can still reincarnate them at any time. The battlefield is a board with square grid spaces, with varying heights (that certain characters can jump up and other cannot) and varying colors. The colors can indicate one of many different status changes, such as Fire Resistance down or Deal 10% Damage, which are determined by the geoblock that sits on a square of the same color. Blocks can be moved by the player or by knockback actions, and if they land on a different color square they transfer the status change with them. This is just the tip of the iceberg, but I think you get the point.
For many people, MMORPGs are extremely complex, with a whole set of strategies, actions, and even vocabulary that one needs to master in order to take on some of the more difficult enemies. I've said before that I play Final Fantasy XIV, and that game has a few fights with some tricky mechanics. Here, let's listen to this simple explanation of the Sephirot Extreme fight by MTQcapture.
Okay, so if you play games like this you might think "Sure, it's tough at first, but once you get it down, you shouldn't have a problem!" and that is true for a lot of people. However, the complexity of the fight is intimidating or even a turn-off to many, and MMO communities aren't always forgiving of people who need to learn the ropes when they're interested in farming (repeatedly performing, usually for a specific item) as quickly as possible. This is a symptom of what I consider to be a rather gross aspect of MMORPGs, in which fun gets harder to have the "higher" the stakes become, but that's a different subject. My point is that if people are faced with this daunting complexity and made to feel like playing with others only makes it harder, well then what point is there to play? Literally none of it is enjoyable to them. I think that's a shame, since there is a lot of fun to be had with a reaction-based fight light Sephirot EX, but one can't forget how overwhelming complexity can be, especially when we take it for granted. (Also, shout out to MTQcapture, because even if you were confused by her strategy, she actually did make it fairly accessible for people who play the game.)
While the above examples represent a complexity that offers rewards for those who master it, there is also the game that is so needlessly complicated that it defeats its own purposes and becomes tedious for no apparent reason. My example for this type of game is Mario's Time Machine.
I hated this game as a kid. Not because it was educational, not because it didn't feature platforming, not because the art was weird. No, it was because deciphering what I was supposed to do was a nightmare! You were thrown into Bowser's Super Mario World-esque Castle, or summer home I guess since it was so much smaller, and find yourself in a room with some objects-like an apple, or a piece of paper- and then you hit a bunch of buttons until you realized that you could make a giant gold thing appear. Okay, so it was Isaac Newton's apple and the Declaration of Independence or something, but it was still hard to tell what to do with them. You then used the time machine to pick a location and a date. Let me remind you, this game was designed to help teach kids about history. So in order to teach kids when Isaac Newton developed the theory of gravity, you... Had to know when Isaac Newton developed the theory of gravity.
While that profoundly counterminds the purpose of the game, that's not the last of the problems. After you pick your place and your year you were then thrown into this bizarre mini-game where Mario is surfing on some flat water, trying to pick up ten mushrooms. Except the mushrooms look very pixely until they are right next to you, as do the spiky bombs that take away all your mushrooms that also inhabit the time lake or wherever we are. You don't know really why you're doing this, and probably vaguely piece together the fact that you need 10 mushrooms and there are also whirlpools in the area, so maybe you use those after you get all 10 mushrooms. Well that's correct, but once you do that... You find yourself back in Bowser's castle. The reason, it turns out, is because you need to pick the exact right year and the exact right place before you'll go back to the spot you need to return the object. You won't really have a way of knowing that, though, because nothing tells you what you did wrong, or even if you did anything wrong. WHY?
Complicated games can be good, but they can also be inaccessible, or just plain bad. The key is to make the complexity reasonable enough that any challenge therein can be explained by the game's setting. You dodge a myriad of moves because world-ending monsters aren't going to play nice and wait for you to hit them. You keep track of everything going on in an sRPG because you're given all the time in the world to pick your move, so you gotta make it count. You... Swerve about on a lake to get mushrooms because sometimes Nintendo hates you.