A lot of those simple games include a scoring mechanism, a lot of the players focus is on beating a score (theirs, a friends, or some online ranking). This is especially true when obtaining a better score is somewhat based on skill, as players try for a mistake-free run.

Also while simple on first appearances, they can have sometimes have a fairly lengthy period of learning e.g. different match effects/combos. And pinball can have a very extensive list of features if you hit things and get the ball in certain places in certain orders ("locked" ramps etc., bonus lives, multi-ball, bonus points on certain bumpers, etc.). And even once the mechanics are known, trying to get that perfect game with no mistakes. And activating the flipper at exactly the right moment to get the ball exactly where needed at the top of the table, and then not straight back down the middle requires a fair bit of skill and practice.

hpdvs2 said:
What keeps a player going through seemingly nearly identical levels?

My simple answer would be: the game's core loop is enjoyable to the player. Or, if you want to put it another way, there's some mechanic(s) in the game that the player finds more enjoyable than the “level” variety aspect you're asking about. I use the word “enjoyable”, but I don't necessarily mean "happiness" or “pleasantness”, but rather someone's willingness to actually spend time playing the game.

I personally enjoy loot pursuit games. Collecting loot, whether it's from killing monsters, opening chests, or crafting, and then using that loot to collect more, better loot is something I just really love. The variety of content not pertaining to the loot mechanics of the game has much less effect on how I enjoy those games most of the time. That's not to say it doesn't matter though, but it amounts more to being a meal's “seasoning” rather than the main dish, for example.

I feel there's only a few genres of games where the “level” variety could actually drive the game itself. One genre that comes to mind is a simulator game where the aim is to provide a realistic experience of something in a real world location, such as driving a car, flying a plane, etc… The other genre that comes to mind is VR based games where the experience might be based on literally a “virtual reality”, so that “reality” usually needs quite a bit of variety. Even in those cases though, the core mechanics of the game presented in the VR format are still highly relevant most of the time though.

From a game design perspective, I think the root of your question lies in the highly debated topic of “theme vs mechanics”: http://www.leagueofgamemakers.com/theme-vs-mechanics-the-false-dichotomy/

I'd highly suggest reading more on that issue, as well as just spending some time just looking up talks about the core game loop. One reference: https://gameanalytics.com/blog/how-to-perfect-your-games-core-loop.html

Adding something unrelated to mechanics or the given example games…

What makes the same level / region enjoyable to visit multiple times for me is a presistent world. Something that got lost in modern games. Example:

In Outcast, if i clear a section from hostile animals, they do not come back for the whole game. Result: My actions have an effect! I have changed the world! The game is real, and i am alive! Yaaay!!! I'm not not bored because of missing animals - no! Instead i remember them. Forever.

In SW Jedi Fallen Order, if i clear a section from hostile animals, they do come back. After i reload, or if i decide to recover my energy during saving. Result: This does not feel real, it's all fakery! My actions have no effect at all. Smoke and mirrors, made to fool me. Facade. It does not matter what i do, i could just die - wouldn't make any difference. And i'm bored from those annoying animals coming back again and again.

The thing that keeps players playing any game, regardless of whether it's the same or varied levels, is game feel/juice. A game with sufficient juice doesn't actually require much at all to keep a player interested - the connection between player and game is enough to stimulate the mind and keep the player thirsty for more.

Consider how much time people have wasted in Mario 64 just jumping around in the garden - there's very few “game mechanics” involved in that (that is, no score, bosses, challenge, levels, progress, etc) and yet it pulls people in. Really, mechanics should reinforce game feel or augment it.

Think like this: you want the “big payoff” moment, so you do something like shake the screen and play a cool sound effect with some other graphical some flare. There's your feel. You reinforce that payoff by linking it to the game mechanic of connecting a chain of dots, and further reinforce it by adding to the players score or changing the background on occasion. The feel is the first thing you design, the mechanics just justify the feel to the player and give them something to work through to get that feel (human brains are weird: if we don't have to work for the payoff, we don't care about it). At that point, it really doesn't matter how trivial or repetitive the mechanics are, provided the payoff is good and spaced out enough so as not to get boring through over-exposure.

Ask yourself, just how “varied” is a game of tetris? I can't find it now, but an article estimated that this single game has wiped out hundreds of thousands of man-hours of work… and it's extremely repetitive. Most of the vastly successful games are. Candy Crush doesn't exactly mix it up much or have advanced progression systems, AAA graphics, deep AI systems, procedurally generated realistic environments or… you get my point. Games are simple. Good games have a good core, and then layer on mechanics to augment that core. So start with your core: ask not what the player can do but what the player should feel.

TLDR: Cram as much game feel into your game, then make mechanics that justify the feely-moments, then worry about things like repetition. You might not ever find a reason to care about it.

One of the harder questions to answer for just about any game that brings absolutely everything into perspective; game play mechanics, graphics, story line, tasks, game play style and more. All of those things have to be mixed to create variability and enthusiasm to keep the player going, another one is how long should the game be … where do you find the balance? Is the game too short or too long?

When I played Mass Effect Andromeda, it was pretty darn repetitive, go to one planet, fight some bad guys, do the same on another planet. However, what kept me glued to the screen was the story line … I really wanted to see what Meridian looked like, I became so obsessed with it that I was determined to be prepared to fight when I got there, so I took advantage of the crafting system to build weapons, did all the side quests to level up and it was nice that I was introduced to a new map style on every planet, snow, dessert, jungle and the occasional weird underground levels.

I think the story line is really what cut it, if you make it suspenseful enough, the player will be motivated to continue and then you keep the path they travel constantly changing and becoming ever so increasingly difficult but not so much that is is annoying.