In Part 1, we defined the core mechanic for 4X and illustrated how it could be seen in exploration, research, and diplomacy. In part 2, we continue examining how the core mechanism manifests itself in other aspects of play.
Unlocking Tools for Victory in eXtermination
Combat is a major system that might seem like it doesn’t unlock anything for the player. But when you stop to think about it, combat is where much of the unlocking comes into focus. Without combat, there would no point in researching new techs or enabling the construction of new units by working your way up a building tree. Building an Armory might unlock the swordsman unit, but it isn’t until combat that you can see what that means. These military tools are intangible until brought to bear on the battlefield.
Also, in a more obvious way, combat is where you unlock the tactical secrets of a game, assuming the game allows it. This is why I think 4X games are best when there’s a tactical screen like in Master of Orion 2 or Age of Wonders 3. However, I do recognize that there are still tactics involved in games like Civilization VI where combat happens at the strategic level. Anyway, tactics are tools for victory just like units or buildings. Uncovering them through combat is an exercise of the core mechanism of 4X.

Endless Space 2 took sort of a step in the right direction by having the tech tree, quests, and anomalies unlock new “combat cards.” These cards are primarily positioning mechanics for your spaceships in battle. The mechanic is interesting but the implementation is dull. What would be much better, would be if engaging in combat earned you new and/or improved combat cards. Thus combat would be used kinda like it is in Stellaris where researching the debris from battles can unlock new, hidden tools for victory (such as new techs) and be a lot more satisfying.

The important thing to remember about combat and its relationship to the core mechanic is that the solutions to winning a battle should not be obvious in good 4X design. The player should have to do some discovering in order to unlock the best strategies. Each unit should provide meaningful options for the player. Capital ships should provide different strategic opportunities than corvettes. Magicians should play differently than spearmen. Artillery should be able to do something tanks can’t. When games fail to have novel tactics unlocked by diverse units, the combat feels bland and rote.
Unlocking Tools for Victory in eXpansion
When a player’s empire expands, there are few consequences in most 4X games other than the most obvious (capturing new territory, expanding the economy, etc.). There might be some kind of anti-city-spam or colony-spam punishing mechanics that unexpectedly kick in, but otherwise, what “new things” does the player get out of it? Perhaps some trade route opportunities or maybe a wonder? Meh.
The fact that expansion, in and of itself, doesn’t unlock new content is a design hole and one that should be examined and rectified by future titles. Let me give you an example of what I’m talking about. In my second or third playthrough of Civilization IV, I remember very clearly when I accidently discovered that I could build an Ironworks in a city that had access to coal and iron. I was blown away. I wondered if there were other combinations that would yield a unique building, so I started settling my cities according to a whole new strategy. Alas, there weren’t, but I think that’s one template (among many) that other games could follow.
The Core Mechanic and Winning
I’ve been hinting about endgame states throughout this article. The endgame in 4X is, in general, a design failure. Rob wrote a great article called “The Endgame and its Follies” back when the site was still fairly new. Despite coming up on being almost three years old, it’s still relevant. 4X endgames, for the most part, suck.
I suggest that the reason the endgame is so awful in 4X is that when players reach that point, the game totally loses its grip on its core mechanism. Once we can’t unlock any new inaccessible content, the game gets boring. I also think that’s why players enjoy the early game so much – there’s all kinds of novel content to chase after. Remember, the core mechanism is what a game is all about and what the players will find most rewarding. Without it, gameplay breaks down entirely.
If designers can find a way to continue to reinforce the core mechanism of 4X (as I’ve identified it) from beginning to end, I firmly believe they’ll solve the late game tedium of the genre. There have been some good attempts like Antarans in Master of Orion 2, External Threats in Polaris Sector, or Fallen Empires in Stellaris, but those games are only touching the surface of what needs to be done.
Well then, one might wonder if combat is the core mechanic in 4X games since all your tech and spells and units go toward winning in that fashion. Well, no, that’s not the case. From the very beginning with Civ, MoO, and MoM, there were ways to win other than combat. That idea has only been expanded on since.

I would suggest that all victory conditions in all well designed 4X games ought to require you to unlock new content. If there is a game out there calling itself 4X but gears everything the player does toward combat including winning through combat, we might not have a 4X game on our hands. It’s probably some type of war game. Its core mechanic would not be unlocking inaccessible tools but instead would be whatever the game used to adjudicate winners on the battlefield.
Now, I’m not saying a game can’t be a 4X unless it has multiple victory conditions. I’m saying that 4X games have multiple victory conditions because they reward players for unlocking content. That’s a small distinction that makes a big difference. A war game with a peacemaking victory condition is still a war game – it’s core mechanic is troop interactions on the battlefield and it rewards the player for mastering those interactions. 4X games are different. You don’t (or at least shouldn’t) be required to master battle as the only way to win.
Core Mechanism vs. Supporting Mechanism
I’m going to dive back into definitions again for just a moment. A core mechanism is the game element the player uses over and over in order to succeed in the game. A supporting mechanism is an element that leads the player back to the core mechanism by enhancing it.
As mentioned earlier, many game types have tools or features that are revealed to the player over time. Does that make them a 4X game? No, of course not. But why they aren’t is a more important question.
Even though RPGs, shooters, fighting games, etc. might all have content that must be discovered through play, that process of discovery is just a byproduct of play, not the point of play. I believe that each of those game genres have different core mechanisms that are not unlocking new content. I’ll go over a few examples in a bit.
Remember I stated that the Core Mechanism is related to rewards. 4X games go to great lengths to immediately reward the players for unlocking blocked content. Any time you spend a required amount of research points, you’ll get a new thing to play with like a spell, a unit, or a technology. Any time you construct a new building, you’ll immediately get a bonus, new unit, new crafting recipes, or access to a previously cordoned off piece of the game like a black market.

Hidden content is going to be part of all games. If all content was apparent to the player right up front, you’d have something more like a puzzle (where you try to just solve the problem in front of you) or a contest (where you try to hone a particular skill until you succeed). The difference is what the game does in response to the player discovering the hidden content. If the game rewards you for doing that right away, then that’s the core mechanic. If you have to take that hidden content and then apply it to some other mechanic that the player does in order to succeed (like discovering the dragon punch in Street Fighter), then the unlocking of inaccessible content is just a supporting mechanism.
The Core Mechanism and Variable Pathways to Victory
I think one thing that successful games do well, is that in any given game your decisions lead to only some of the full range of tools for victory being unlocked and made available. Games become more replayable when you can unlock a different set of tools in the next session and craft a different strategy as a result.
The Endless Legend example about Heroes leveling up is a perfect case in point. Heroes have three skill trees but in a given game you’ll never be able unlock every skill in each tree, and so you are forced to make some decisions in what “tools” you have available. This simultaneously makes that individual playthrough more unique and the game as a whole more replayable as you get to try out different sets of tools. Also, if the types of heroes you get varies from game to game, it keeps the mechanic fresh. This idea can be applied universally throughout a 4X game’s various systems.
The Core Mechanic in 4X is Different from Other Genres
It might seem problematic at first to use “unlocking hidden tools” as a standard by which we determine whether a game is or isn’t 4X since so many games from MOBAs to Roguelikes can be said to have hidden content that is unlocked through play. I would reply, well of course they do! But those aren’t the core mechanism for those games. Unlocking content simply supports the core mechanisms for those genres. I’m going to go through several examples of core mechanics in other genres to show how they are different from 4X.

Platformers are about the Jump ability. FPS games are about relative positioning. Hardcore RTS games are about actions per minute. These games might have some kind of XP system that unlocks new weapons, or super jumps, or whatever. But that XP system is not what those games are about. It isn’t a core mechanism. Fighting games like Mortal Kombat have all kinds of hidden combos, but the core mechanic of the game isn’t finding them; it’s striking your opponent. That’s what leads you to winning. That’s what the game rewards.
While a CRPG may have lots of content that is locked, the game isn’t so much rewarding the action of unlocking that content but instead rewards whatever it is you have to do to earn that content such as killing monsters, fulfilling quests, etc. The core mechanic of an RPG is typically the advancement system. I’m not saying there can’t be emergent gameplay like in Skyrim or The Witcher 3 where players focus more on just exploring the world and discovering its mysteries instead of advancing their characters, but that emergent gameplay is not the core mechanism, which is what I’m laser focussed on in this article.
Action RPGs like Diablo are about killing monsters. You aren’t rewarded just for hurting the monster. You’re not rewarded for discovering new monsters. You’re only rewarded for killing. The new skills and weapons you unlock through various advancement systems and quests are mainly there to make you a more efficient killer. You’re not going to beat Diablo 3 by maxing out your skill tree, but you are going to beat Endless Space 1 by researching the Pan-Galactic Society.
Disproving this Core Mechanism Theory for 4X
One way to disprove my core mechanism theory is to find other game genres that share the same core mechanism, thus showing that what I believe to be the 4X core mechanism is endemic to many other video game genres. But as I showed in the previous section, that just isn’t the case.
Conversely, we could find a game that is universally recognized as 4X that doesn’t do this at all. At the moment, I’m strapped to find examples. If you can, please post them in the comments below.

Another way to disprove my theory would be to find an alternate core mechanism that does a better job of describing what 4X games are all about. The reason I went through so many 4X subsystems in the first few sections of this article was an attempt to show how consistently we can see that unlocking hidden tools for victory is at the heart of (or should be at the heart) good 4X gameplay.
So, for 4X games, opening up unique game aspects that were previously unavailable is what players do almost all the time until it isn’t, which is where 4X games start to suck. At that point, the game stops giving you its core mechanism, and you’re left to figure it out on your own. Imagine if you couldn’t hit your opponent in the last 10 seconds of a Street Fighter match. You just had to wait for time to run out and the player with the lowest life total lost. How boring would that be? That’s what would happen if a fighting game lost its core mechanic, and that’s often how 4X games feel at the end when there’s nothing new left to discover.
If you feel there is an alternative core mechanism, please post it in the comments below. I’m very keen to hear opposing points of view.
With This in Mind, What’s a 4X?
As I mentioned in the introduction, the idea for this article was sparked during a (very friendly and respectful) debate I had with Oliver over the nature of the 4X genre. The debate itself, though, was partially the result of a conversation we were having about a couple other games. Dallin was writing about Total War: Warhammer while I was struggling with Last Days of Old Earth. When I went to write my review/eXcursion, I wasn’t sure which type of article to use. LDoOE clearly had all four X’s present, but both Rob (who was still with us at the time) and I agreed that it certainly wasn’t a 4X game. But why?

It wasn’t until I realized that the core mechanism of that game is the strategic expenditure of limited resources, not unlocking inaccessible content that I had a justification for not doing our typical 5X review for it. For me, it was an epiphany.
What’s also interesting is that, in response to my article, Haldur (who is one of our terrific community members) pointed out the historical application of the “4X” label. He correctly notes that it was used to describe the original Master of Orion and not Civilization 1. He also notes that games that are older than MoO or Civ are also considered by some as “4X” forerunners or proto-4X games. Hence, it can be very problematic to label a game as 4X or not-4X without taking the entire historical context of the term and the genre into account.
To which I reply, yep that’s true! Which is why I (and others) feel that “4X” is a horrible way to describe 4X games. Labeling a game based solely on the existence of eXploration, eXpansion, eXploitation, and eXtermination is far too broad to be really useful. Any time you bring up 4X, you have to ask how the other person wants to define it. “Should we include games like EU4 and Thea or are we limiting this to Civ-like games?”
By focussing on the core mechanism rather than the four X’s, we can get a better handle on what is or isn’t the type of game that spawned eXplorminate and why some are more fun than others.
So let’s look at some examples of games we at eXplorminate have treated as 4X that probably aren’t. First, let’s examine Apollo4X. The core mechanism of that game can’t be “unlocking hidden tools for victory” since nearly everything is revealed to the player upfront. I would suggest instead that the core mechanism is resource trading since that is both what leads to victory and what the player focuses most of his/her decision making on.

Next, what about Europa Universalis IV and Crusader Kings 2? I think most people would probably go ahead and label them as Grand Strategy instead of 4X, but what makes them not 4X? I would suggest that since these games make no real attempt to keep information out of the hands of the player, the core mechanism is not “unlocking inaccessible content.” If I had to hazard a guess at their core mechanic, I would suggest that it might be managing relationships. Same goes for Stellar Monarch. These are as much political games as they are war games. War is just a tool to enforce or destroy a relationship, so I have a sense that might be right. For the purposes of this article, though, it doesn’t matter if I correctly identify what their core mechanism is but rather, what it isn’t.
I think Total War: Rome II basically fits into the Grand Strategy category as well, though it’s definitely not a political game like EU4 and CK2. It shares many of the same traits and like the aforementioned titles and certainly is not all about opening up hidden game elements.

Okay that seems simple enough, but what about so called “hybrid” games likeArcane Sorcery, Thea: The Awakening, and Sorcerer King? These are somewhat more problematic. For Arcane Sorcery, I would suggest it is an incoherent design, i.e. it doesn’t know what its core mechanism is. There is some content unlocking going on with its un-randomized spell research, specialized units that are unlocked through a rather convoluted and absolutely concealed building tree, and emergent though rudimentary tactics on the battle screen. Yet at the same time, there’s no mystery about the maps (they’re not even procedurally generated), and you know what your opponent’s forces are and where they are at all times. I’m honestly not sure I could really identify what Arcane Sorcery is about.
For Thea, it’s much easier. Its core mechanic is unquestionably unlocking inaccessible content. In fact, of any game I’ve played, I think Thea does the best job from beginning to end of reinforcing its core mechanic. The research trees keep all kinds of things hidden from the player. The quest system unlocks new stories and new allies at all stages of the game: beginning, middle, and end. The quests even lead to a satisfying victory, which is a rare example of the endgame in a 4X not being boring.
The crafting system in Thea is also a fantastic example of unlocking content as the myriad of recipe combinations always yields a surprising result AND those results can be further influenced by the quality of the item produced. The player can’t know for sure how an item will turn out until it’s finished, and each type has different bonuses and stats. Also, crafting with gemstones bestows random abilities on weapons and armor, so the whole crafting system turns into a wonderful roulette system that keeps the player engaged throughout play.
I would suggest that Sorcerer King, much like Thea, is a 4X game with the core mechanism I’ve described – at least on the first playthrough. Quests, crafting recipies, hero abilities, spell research, building trees, are all hidden tools that must be discovered in order to win. Even the great Sorcerer King himself provides novel content that is revealed as a result of player actions over time, and revealing that content is the point of play which leads to victory.
SK’s biggest design flaw is its lack of content. It would be a better 4X and reinforce its core mechanism more if there was more content to be unlocked. After the first playthrough, one might be able to argue that the game becomes much more like a puzzle than a game, especially on one of the non-procedurally generated maps. But, as it is, SK qualifies in my estimation.
I understand that this might pose some difficulties with the traditional use of the term 4X, especially for those that really attach that term to its original use. I would propose, however, that Master of Orion was never really about eXploring, eXpanding, eXploiting, and eXterminating. That was just one heuristic an author used to describe a very complex game. Those four things helped reinforce its core mechanism. Instead, I believe the game was about unlocking cool content in unexpected ways and then using that discovered content to win. Everything from the different faction abilities to the different techs to the different planet types and ship designs reinforces this.
Perhaps one might be able to say that the four X’s are the methods by which one engages the core mechanism of a 4X game. That might reconcile my theory with tradition, if tradition is even worth reconciling with. I’ll leave that up to further discussion in the comments and our message boards.
Why Bother Identifying the 4X Core Mechanism?
I think there are several benefits in identifying and discussing what the core mechanism of our genre is and what it could or should be going forward.

First, I believe that 4X game design would improve greatly if it focused more on its core mechanism of unlocking content rather than just trying to fit the Wittgenstein Family of 4X traits (as discussed in part one). In my opinion, the Wittgenstein road leads to a hundred MoO clones and general disappointment with nearly every 4X title that comes out. Having all four X’s doesn’t guarantee a good game. There has to be more to it than that.
Second, as the previous section showed, it’s much easier to talk about what is or isn’t a 4X when you look at the foundation of all gameplay rather than just eXplore, eXpand, eXploit, and eXterminate. I don’t think that many people would argue against me saying that there’s a lot more to a 4X game than just those four things. Also, I don’t think listing a big bunch of subsystems most 4X games possess is all that useful either since that straightjackets future design and will ultimately crumble under its own cumbersome weight as new innovations are continuously piled on.
Third, I think that by examining a 4X game’s subsystems through the lens of the core mechanism, we can better evaluate whether a design is good or bad. If a subsystem does not support the core mechanic well, then then I think we could say it’s probably not well designed or maybe not even necessary. Thus identifying a core mechanism provides a much more useful tool for discussing game quality.
Strategy and the Core Mechanism
You might be thinking to yourself, “4X games are first and foremost strategy games. I don’t see how unlocking content is related to strategy at all.” Good point, I haven’t spoken about that much. The reason is that strategy is not a mechanic or even a game system, and this article is focussed on game mechanisms.
Strategy is a series of choices made by the human player facing varying degrees of uncertainty. The strategy in 4X comes as an emergent property of finding newer and more efficient ways to unlock the new tools that lead to winning. You can’t design a strategy. If you try, what you’re designing is a solution. 4X is at its best when it presents you with evolving problems and tools, then forces you to figure out the solutions on your own.

4X games provide rules that stipulate what conditions have to be met in a game in order to make novel content available (spend 100 research points on this technology, build a wizards’ guild to get access to warlocks, etc.). However, games do not prescribe to the player exactly how or when to do that. If they did, they wouldn’t be games anymore they’d be more like a puzzle you’d have to solve. See Oliver’s excellent article about strategy for more description on the difference between puzzles and games.
4X is best when the player is in control of the methods used to engage the core mechanism. The game will provide context and rewards for those methods, but the player is empowered to strategically choose how, when, and why each of the various sub-systems are engaged (which, in a good design, should all reinforce and support the core mechanism). Again, Oliver’s article “This Thing Called Strategy” is a good read if you want to learn more about the importance of strategy and tactics in a 4X game. That article and this one go hand in hand.
When it comes to strategy, I believe designers should mainly be concerned with making sure there are multiple viable ways to achieve one or more victory types through the core mechanism and the subsystems that reinforce and support the core mechanism. The player will then figure out which strategy suits his or her play style the best.
Closing
As far as I can tell, “unlocking hidden tools for victory” is about the best definition for a 4X core mechanism we can attain at the moment. Ideally, the core mechanism of a well-designed 4X game would be “unlocking previously inaccessible and novel content at variable rates,” but we know a lot of games in our genre don’t do all that and designing game that way is incredibly hard.

I can see plenty of potential pitfalls in discussing this. One might challenge the entire concept of a core mechanism. Is it real? Can such a thing be verified to exist in all games? I think it does, but I’m not sure it’s possible to prove it absolutely, eternally, and objectively. It is a theory, afterall.
Readers might be tempted to use certain 4X games with bad design to disprove this theory. Game quality matters. If the designers and developer team lost focus as they went through the process of producing the game it wouldn’t necessarily disprove anything. It would just mean they did a bad job executing the implementation of the core mechanism throughout their game.
It’s my hope that this article sparks a good debate, and if it turns out that I have correctly identified the 4X core mechanism, then it is also my hope that this article provides designers with some new insight into their craft. I know I would be asking a lot of designers to change the way they approach 4X and at the same time, develop ways to communicate that new approach to the player. However, I have faith in their creativity to do so. I love this genre and want to see it improve. That’s the entire purpose of what I’ve done here. In the end, what matters most to me is improving the state of game design in our genre.