The short answer
Two words: opt-in complexity.
How to keep your gamers happy
The happy path is simple.
- People who want simplicity will be happy with your simple mechanics.
- People who want complexity will be happy with your complex mechanics.
This is always going to be true of any mechanic you evaluate. The unhappy path is more interesting here.
- People who want complexity will quickly bore of your game, assuming they even played it, which would only happen if it wasn't already obvious how simple it was.
- People who want simplicity will feel unable to play your game with complex mechanics, leading to them either not engaging with your game or regretting their purchase.
In either case, you're going to get negative reviews about bad game design (keep in mind that people are more likely to say "badly designed game" rather than "not the kind of mechanics I personally was looking for"), and missed sales (double whammy: both from players looking at your game and players reading those reviews).
Opt-in complexity mitigates the unhappy path. Let's look at an example: Civilization 6. If you already know the game, I suggest you still skim this analysis because it's going to bring up topics that are relevant for the conclusion of this answer.
We're going to try and cater to three kinds of players: the noob, the player, and the expert.
- The noob doesn't want to think, he just wants to play the game.
- The player is looking to make meaningful decisions, but mostly for thematic flavor.
- The expert is looking to squeeze every inch out of the game's mechanics that they can.
Level 1 - the noob
The key gameplay in Civ 6 centers around having cities which produce resources for you. Each city outputs different amounts of resources based on the surrounding environment that it is built it. You can see the generated resources marked in yellow in this screenshot.
The more your city grows (population) and the more you build it up, the more resources the city will output. This is something all players will understand.
When you start the game, you are asked to choose where to settle your city, and the game will highlight specific tiles for you to suggest that this would be a good site to build.
The noob won't question the icons, they'll just build it there. Other than the game forcing them to select what to build in the city, there's no real further work required for that city to grow and thrive. It will generated a balanced output of all resources and will automatically work to avoid starvation of its populace, looking for a happy middle between growth and output.
Level 2 - the player
The player, however, wouldn't be happy that they can't control their city. After all, they've just started a war and really need faster production of military units.
Opt-in complexity kicks in, making the player able to shift the city's focus to disproportionately output one resource (while still avoiding starvation and maintaining growth). Maybe you already noticed in the previous screenshot, but maybe you didn't, the UI actually lets you target a specific resource, marked in yellow on the below screenshot.
This provides an additional level of control. It's more complex, but it allows you more fine-grained control.
The noob rejects this kind of complexity, that's not the fun part of the game for him. But because the game is built in a way that this complexity needed to be opted in to, the noob never had to even think or know about the existence of city focuses.
The player is now happy, they can shift their cities to meet their evolving needs, to within a reasonable degree. They still need to make sure that they build their cities in a good location, but they can have them adapt.
Level 3 - the expert
The expert, however, is not happy that the game is still making decisions on how to implement that focus. For example, the game has assigned a pop to a tile that generates 4 food, 2 production and 3 gold. But there's a tile with 3 production (and nothing else). Clearly, it's not maximizing production then, is it?
While the player wants his city to remain solvent at all times, just with a shifted focus, the expert player wants to be able to eat the cost of their decisions. If they're in a war that is coming close to wiping them out, or it's a city that they have no long term interest in, they will happily starve their city or let them run into negative cost for a while if it gets them that extra point of production.
Opt-in complexity kicks in again. The game allows the expert to manually assign the population to specific tiles (accessed via the button marked in yellow). This enables them to indicate how they want each tile to be staffed (marked in red).
I can't elaborate on it all, but there's a ton of features here. The expert is able to rigorously assign population the way they want to, but they can also opt to only guarantee that certain tiles are definitely staffed (notice the lock icons in the screenshot), while still letting the game figure out what to do with the rest of the population in order to balance out the city's solvency, and what tiles it's allowed to reassign existing population (or assign new population) to.
If a player wanted to, they could revisit this assignment every single turn. Players who play on the highest difficulty level tend to do so in the early game, just to eek out an extra point here or there which means that you e.g. build a military unit one turn faster at the accepted cost of e.g. city growth.
The noob might click that yellow button once, will not even begin to figure out what it does, and will leave that part of the UI never to return. They are still happy just letting the city manage itself.
The player might be interested to find this screen, but they'll generally not bother with the complexities of now bearing the responsibility of keeping your city sustainable, instead favoring the easier city focus buttons.
Conclusion
Opt-in complexity keeps players happy within the level of complexity that they want, while not creating impassable obstacles for players who don't like this added level of complexity. At no point was the noob ever inconvenienced by needing to deal with or respond to complexities that they never even cared about in the first place. They were able to happily ignore that hidden complexity and not deal with it at all.
One very important thing to point out here is that the game always works with explicit population-to-tile assignments. The mechanics didn't really change, the game simply provided an automated way of figuring out the reasonable assignments in ways that non-expert players wouldn't want to learn themselves.
The takeaway here is that if you want to cater to multiple levels of playstyles you should build your game to implement the most complex mechanics that you feel like using, and then you would be able to expand your target demographic by adding automations on top of the complex mechanics, so as to hide the more difficult parts of those mechanics.
This also ensures fairness. If the simpler gameplay used different mechanics under the hood, there's probably going to be some rounding errors where some gameplay negatively impacts players who take on the more complex mechanics, and that's not what you want (it's going to make the experts very unhappy).
The ideal is that the simpler versions of the same mechanics require little to no user knowledge or input, they still provide a reasonable outcome, but the more complex versions should yield a more efficient playstyle. That added efficiency is the reward that players get for the cost of engaging with the complex mechanics - this is exactly what players who like playing complex games are looking for: optimization and marginal benefits.
