Mechanical depth is the number of meaningful decisions a game system can produce from a small set of rules. Mechanical complexity is the raw count of rules, inputs, states, and exceptions a player has to track before those decisions become legible. In competitive platformers, fighting games, and speedrunning, the two get sold as the same thing all the time. They are not. A game can have a six-button layout, three stances, and a 40-page movelist and still collapse into one dominant option. A game with two buttons and a jump can produce years of routing arguments. This article is for players who want to know why some games stay interesting after 5,000 hours and others die after the first balance patch.
I am Jax Moreno, and this is the kind of question I chase on suitablyflip.com: not whether a game feels good in a trailer, but whether its mechanics hold up under frame data, hand strain, and tournament pressure. The distinction between depth and complexity is the foundation for every other argument on this site. If we cannot separate the two, we cannot talk honestly about input latency, controller ergonomics, or why a speedrun route is beautiful instead of merely long.

Defining the Terms Without Marketing Fluff
Mechanical complexity is easy to measure. Count the buttons. Count the cancel windows. Count the unique states a character can enter. Count the exceptions to the exceptions. A game with 40 special moves, 12 defensive options, and three meters is complex. That is a fact, not a judgment.
Mechanical depth is harder to measure because it is about the shape of the decision space. Depth asks: how many distinct, viable choices does a player actually have at a given moment? How often does the correct choice change based on context? How much can a skilled player differentiate themselves from a competent one? A deep game can be simple. A complex game can be shallow. The two properties are correlated in some designs and inversely correlated in others.
Fighting game players have lived with this tension for decades. Street Fighter II has a small movelist by modern standards, but the spacing, throw, and reversal triangle still generates new situations. Some modern fighters ship with 30-hit auto-combos and a movelist that scrolls for days, yet neutral play reduces to two or three safe pokes. The complexity is in the menus. The depth is in the spacing.
Why the Distinction Matters for Competitive Platformers
Competitive platformers are a useful test case because their input vocabulary is tiny. Run, jump, maybe a dash or a wall kick. That is often the entire moveset. If depth required complexity, every platformer would be solved within a week. Instead, games like Celeste, Super Meat Boy, and the Kaizo Mario tradition produce years of routing and tech discovery from a handful of verbs.
The depth comes from how those verbs interact with level geometry, momentum, and frame windows. A wall jump is not one move. It is a family of moves depending on when you press jump, how long you hold it, whether you are rising or falling, and what the wall is made of. The game does not need to list all of those as separate moves. The physics engine creates them for free. That is depth emerging from a simple ruleset.
Complexity, by contrast, would be adding a dedicated button for each wall-jump variant. The player would have more to memorize, but not necessarily more to decide. The decision space might even shrink, because the game has now told you which tool to use in which situation. The player is no longer reading the physics; they are reading the manual.

Input Latency as a Depth Multiplier
Input latency is where the depth-complexity distinction becomes physical. A game with high input latency can still be complex. It can have dozens of moves and systems. But the latency eats into the player’s ability to make contextual decisions. If your reversal comes out three frames late, the decision to reversal is no longer a read; it is a gamble on the game’s internal clock. The depth is still there on paper, but the player cannot access it reliably.
This is why speedrunners and fighting game players obsess over frame data and display lag. A one-frame difference can turn a deep interaction into a coin flip. The game’s mechanical depth has not changed. The player’s access to that depth has. When I test a controller or a display, I am not asking whether the game is complex. I am asking whether the game’s depth survives the trip from my hands to the screen.
Retro games often have an advantage here because they were built for CRT displays and direct controller polling. Modern ports sometimes add layers of buffering, vsync, and input translation that add complexity to the pipeline without adding depth to the game. The player feels the difference immediately, even if they cannot name it. That feeling is the gap between the game’s mechanical depth and the system’s mechanical complexity.
Controller Ergonomics and the Cost of Complexity
Complexity has a physical cost. Every additional input is a demand on the player’s hands. A game that requires constant piano-style inputs across four shoulder buttons and two face buttons may be complex, but it may also be unplayable for long sessions. The depth of the game does not matter if the player’s hands give out before the decision space opens up.
Fighting game players know this from experience. A character with a high execution barrier may be deep, but the depth is gated behind hand health. A simpler character with fewer inputs can still be deep if the decisions are hard. The question is not whether the game asks a lot of the player. The question is whether the physical cost buys meaningful decisions or just more button presses.
Speedrunners face the same tradeoff. A route that requires frame-perfect inputs for two hours may be complex, but it may also be unsustainable. The best routes are often the ones that reduce physical complexity while preserving the depth of the decision space. A well-designed speedrun route is a lesson in mechanical economy: how much depth can you keep while cutting the complexity that hurts your hands and your consistency?
Retro Ingenuity vs. Modern Shortcuts
Retro games often achieved depth through constraint. The hardware was limited, so designers had to make every rule count. A single jump arc in Super Mario Bros. is a masterclass in depth through simplicity. The jump height, the air control, the acceleration, the landing lag — all of it is tuned so that a two-button game can produce dozens of distinct platforming situations. The complexity is low. The depth is enormous.
Modern games sometimes take the opposite approach. They add systems to create the appearance of depth. A skill tree with 50 nodes, a crafting system, a parry, a dodge, a block, a counter, a super meter, a rage meter, a stamina bar. Each system is simple on its own, but together they create a wall of complexity. The player spends hours learning the systems before they can even begin to make meaningful decisions. That is not depth. That is onboarding friction wearing a depth costume.
I am not nostalgic for retro games because they are old. I am interested in them because they often solved the depth-complexity problem with fewer resources. That is worth studying, not worshipping. The goal is not to make modern games retro. The goal is to make modern games as economical with their mechanics as the best retro games were.
Case Study: The One-Button Fighting Game
Imagine a fighting game with one button. Press it to attack. That is the entire moveset. Is the game deep? It depends on what the attack does and how the rest of the game is built. If the attack has variable range, variable speed, and variable recovery based on timing and spacing, then one button can produce a surprising amount of depth. The player is not choosing between moves. The player is choosing between moments.
Now imagine a fighting game with 40 buttons. Each button does one specific thing. The game is complex, but the decisions are trivial because the game has already mapped every situation to a button. The player is not making choices. The player is executing a lookup table. That is the difference between depth and complexity in its purest form.
Real games fall somewhere between these extremes. The best fighting games use a small number of buttons to create a large number of situations. The worst ones use a large number of buttons to create a small number of situations. The movelist is not the game. The decision space is the game.
How to Evaluate a Game’s Depth Without Playing It for 100 Hours
You can often spot the difference between depth and complexity in the first hour. Ask yourself: am I making decisions, or am I learning rules? If the first hour is spent memorizing systems, the game may be complex. If the first hour is spent making interesting choices with a small set of tools, the game may be deep. The best games do both: they teach you the rules quickly and then let you play with them.
Another test: watch a high-level player. If the high-level play looks like a completely different game from what you are playing, the game may have depth. If the high-level play looks like the same game with faster inputs, the game may be complex but shallow. Depth creates visible skill expression. Complexity creates visible memorization.
A third test: ask what happens when you remove a system. If the game falls apart, the system was load-bearing. If the game plays basically the same, the system was decorative complexity. The best games are the ones where every system is load-bearing, and the load is carried by a small number of well-tuned rules.

The Speedrunning Perspective: Routing as Depth Mining
Speedrunners are the best depth miners in the world. They take a game that was designed for casual play and find the hidden decision space inside it. A speedrun route is not just a sequence of inputs. It is an argument about which mechanics are deep enough to exploit and which are complex enough to skip.
When a speedrunner finds a new skip, they are often reducing complexity. They are cutting out a section of the game that was complex but not deep. The skip is a statement: this part of the game was not worth the time. The parts of the game that survive in the route are the parts that have depth. The route is a map of the game’s actual decision space, not its advertised feature list.
This is why speedrunning communities argue so much about glitches and skips. A glitch that removes a complex section is celebrated. A glitch that removes a deep section is controversial. The community is not just arguing about rules. They are arguing about what makes the game worth playing. That argument is the depth-complexity distinction in action.
Common Misconceptions About Depth and Complexity
One common misconception is that more mechanics always means more depth. This is false. Adding mechanics can reduce depth by making the correct choice obvious. If a game gives you a parry that beats every attack, the parry is not a deep option. It is a dominant strategy. The game becomes shallower because the decision space collapses.
Another misconception is that simple games are automatically deep. This is also false. A game with one button and no meaningful variation is not deep. It is just simple. Depth requires that the simple rules produce complex outcomes. If the rules are simple and the outcomes are simple, the game is shallow. Simplicity is not a virtue on its own. It is a virtue when it produces depth.
A third misconception is that depth is subjective. It is not entirely subjective. You can measure the number of viable options in a given situation. You can measure how often the correct option changes based on context. You can measure how much a skilled player outperforms a competent one. These are not perfect measurements, but they are real. Depth is not just a feeling. It is a property of the game’s decision space.
Practical Takeaways for Players and Designers
For players: when you are choosing a new game to invest in, look for depth, not complexity. A game with a huge movelist may be fun to explore for a week, but a game with a small movelist and a deep decision space will keep you coming back for years. The best test is to watch high-level play and ask whether the players are making decisions you can understand but not execute. If the decisions are legible, the game has depth. If the decisions are hidden behind a wall of systems, the game may just be complex.
For designers: every mechanic you add should earn its place. Ask what decision the mechanic creates that did not exist before. If the answer is “none,” the mechanic is complexity without depth. Cut it. The best games are the ones where every rule is doing work. That is the difference between a game that is fun to learn and a game that is fun to master.
For speedrunners and competitive players: the depth-complexity distinction is a tool for routing and matchup analysis. When you are optimizing a route, ask whether a section is complex or deep. If it is complex, look for a skip. If it is deep, look for a better strategy. The same applies to fighting game matchups. A matchup that is complex but shallow is a knowledge check. A matchup that is simple but deep is a skill check. The skill checks are the ones worth practicing.
FAQ
What is the difference between mechanical depth and mechanical complexity?
Mechanical complexity is the number of rules, inputs, and systems in a game. Mechanical depth is the number of meaningful decisions those systems produce. A game can be complex without being deep, and deep without being complex. The distinction matters because complexity costs time and hand health, while depth is what keeps a game interesting over thousands of hours.
Can a simple game be deep?
Yes. Games like Super Mario Bros., Celeste, and many fighting games with small movelists are simple in their input vocabulary but deep in their decision space. The depth comes from how a small set of rules interacts with physics, spacing, and timing. A simple game is not automatically deep, but simplicity is often the best foundation for depth because it lets the player focus on decisions instead of memorization.
How does input latency affect mechanical depth?
Input latency does not change the game’s theoretical depth, but it changes the player’s access to that depth. If a reversal or a frame-perfect jump is delayed by even a few frames, the player can no longer make the decision reliably. The depth is still there on paper, but the player cannot reach it. That is why competitive players care so much about display lag, controller polling, and frame data.
Why do speedrunners care about the depth-complexity distinction?
Speedrunners use the distinction to decide what to skip and what to optimize. A complex section that does not produce interesting decisions is a candidate for a skip. A deep section that produces many viable strategies is worth routing carefully. The speedrun route is a map of the game’s actual decision space, and the depth-complexity distinction is the compass.
Where This Leads on suitablyflip.com
This article is the foundation for a series of pieces on how specific games handle the depth-complexity tradeoff. Next, I want to look at a single mechanic — the wall jump — and trace how different platformers have tuned it for depth or buried it in complexity. After that, I want to examine fighting game movelists and ask which characters are deep with small kits and which are shallow with large ones. If you have a game you want me to analyze through this lens, send it my way. The best arguments on this site start with a reader who noticed something I missed.










