Case Study 2: Baba Is You --- Mechanics as Content

The Rules Are on the Floor

Most games have rules that are invisible. The player does not see the code that governs gravity, collision detection, or enemy behavior. They experience the effects of rules, but the rules themselves are abstracted away --- implemented in source code, hidden behind the game's interface.

Baba Is You, released in 2019 by solo Finnish developer Arvi Teikari (known as Hempuli), does something radical: it makes the rules visible. And pushable. And breakable. And rearrangeable.

In Baba Is You, the rules of each puzzle are physically present in the game world as text tiles. "BABA IS YOU" means you control the character named Baba. "WALL IS STOP" means walls are solid. "FLAG IS WIN" means touching the flag wins the level. These rules are not metaphors or UI elements --- they are objects on the game's grid, subject to the same physics as everything else. You can walk up to them and push them.

Push "BABA" away from "IS YOU" and you lose control of Baba. Push "ROCK" in front of "IS YOU" and now you are a rock. Push "WALL" away from "IS STOP" and walls stop being solid --- you walk through them. Push "FLAG" in front of "IS YOU" and you become the flag. Then push "BABA IS WIN" and walk Baba into the flag (which is you), and you win.

This is not a gimmick. It is a complete reimagining of what game mechanics can be.

Two Verbs, Infinite Rules

Baba Is You has two mechanical verbs: move (in four cardinal directions) and push (walk into an object to displace it by one tile). That is the entire input vocabulary. Four directions. Contact-based pushing. No jump, no attack, no dash, no inventory, no crafting, no combat.

The depth comes entirely from what you can push. Because the rules of the game are physical objects, pushing rule words creates, destroys, and modifies the constraints governing the puzzle. The mechanic is not "solve the puzzle." The mechanic is "change the rules of the puzzle until a solution is possible."

This distinction is essential. In most puzzle games, the rules are fixed and the player must find a solution within those rules. In Baba Is You, the rules are the primary thing you manipulate. The puzzle is not "given these constraints, reach the goal." The puzzle is "given the ability to change constraints, create a set of constraints that allows you to reach the goal."

The result is a game where the player is not just playing within the system --- they are playing with the system. Every level is a meta-puzzle about the nature of rules themselves.

How the Mechanic Subverts Fixed Design

Traditional game mechanics are what the designer decides they are. If Mario can jump, it is because the designers coded jumping. If Link can swing a sword, it is because the designers coded sword-swinging. The player has no ability to change what verbs are available --- they can only choose when and where to use the verbs they are given.

Baba Is You subverts this entirely. The player determines what the verbs are.

Identity Is a Rule

"BABA IS YOU" is not a character assignment --- it is a rule tile, and it can be changed. Push "ROCK" in front of "IS YOU" and you become a rock. Push "WALL IS YOU" and you become every wall simultaneously, all moving in the same direction when you press an arrow key. Push "TEXT IS YOU" and you become the text tiles themselves --- the words that form the rules. You are now controlling the rules directly, pushing them from inside the system.

The concept of "who you are" in a game is usually the most fixed mechanic. You are Mario. You are Link. You are the spaceship. Baba Is You makes identity a variable. This one decision --- identity as a modifiable rule --- cascades into hundreds of puzzle designs that would be impossible in any other framework.

Properties Are Rules

"WALL IS STOP" makes walls solid. Remove the rule and walls become permeable. "WATER IS SINK" makes water deadly. Remove the rule and water becomes walkable. "LAVA IS HOT" and "HOT IS DEFEAT" are two rules that, together, make lava kill you. Break either one and lava becomes harmless.

Every property in the game --- solidity, lethality, pushability, winnability --- is a rule tile that can be manipulated. The player does not experience these properties as fixed laws of the universe. They experience them as opinions held by the universe that can be changed.

This reframing has profound design implications. In most games, the designer decides which objects are dangerous and which are safe, and the player navigates accordingly. In Baba Is You, the player decides which objects are dangerous and which are safe, within the constraints of the available rule tiles. The designer's control is one level removed: they control which rule tiles are present in each level, not which rules are active. The player activates, deactivates, and rearranges the available rules to create a solvable configuration.

Win Conditions Are Rules

"FLAG IS WIN" seems like a fixture --- of course the flag is the win condition. But you can push "BABA IS WIN" and then walk any object into Baba to win. You can push "ALL IS WIN" and everything becomes a win condition --- touching anything ends the level. You can even create paradoxes: make yourself the win condition, and then... what? You need another entity to touch you, but you are the only entity the player controls. Unless you change who you control.

The win condition itself is a pushable, modifiable rule. The goal of the game is not fixed by the designer; it is determined by the player's manipulation of rule tiles. This is unprecedented. In nearly every other game, the designer defines the win state. In Baba Is You, the win state is part of the design space the player operates within.

Mechanics as Content

Most games distinguish between mechanics (the tools the player uses) and content (the situations those tools are applied to). Mechanics are verbs. Content is levels, enemies, puzzles, story beats --- the stuff the designer creates for the player to engage with using the mechanics.

Baba Is You collapses this distinction. The mechanics are the content. Each level introduces a new combination of rule tiles, and the challenge is figuring out how those specific tiles can be rearranged to produce a win state. The player is not learning new verbs across the game (move and push are the only verbs from start to finish). They are encountering new rule tile configurations --- new ways in which the two verbs interact with the system.

This is an extraordinarily efficient design. With two verbs and a vocabulary of approximately thirty rule words (BABA, ROCK, WALL, FLAG, WATER, IS, AND, HAS, MAKE, PUSH, STOP, WIN, DEFEAT, SINK, YOU, FLOAT, HOT, MELT, OPEN, SHUT, MOVE, TELE, EMPTY, NOT, and a few others), Baba Is You generates over 200 puzzles. The combinatorial explosion of rule interactions produces more unique puzzle states than most games achieve with dozens of mechanics.

What Baba Is You Teaches About Mechanic Design

Lesson 1: Simplicity of Input, Complexity of Consequence

Two verbs. Move and push. A three-year-old can understand the inputs. The consequences of those inputs --- the cascading effects of rule changes on the puzzle state --- are so complex that some puzzles take experienced players hours to solve. The genius is not in the inputs. It is in the system that interprets the inputs.

This is a lesson that applies far beyond puzzle games. The best mechanics are simple to perform and complex in their effects. Mario's jump is one button. Its interaction with momentum, gravity, and level geometry produces infinite variety. Slay the Spire's card play is "click a card." Its interaction with energy, deck composition, and enemy behavior produces strategic depth that sustains hundreds of hours of play.

Lesson 2: Let Players Change the Rules

Baba Is You is an extreme example, but the principle scales. Any time you let the player modify the system, not just act within it, you create a qualitatively different kind of engagement. Minecraft lets players modify the world. Noita lets players modify the physics (by mixing spell components). Dwarf Fortress lets players modify the rules of an entire civilization simulation through dwarf behavior assignments.

Modifiable rules do not mean your game needs to be a meta-puzzle. They mean that giving the player the ability to change how the system works --- even in small ways --- produces a sense of agency and creativity that fixed systems cannot match.

Lesson 3: Constraints Generate Puzzles

Each level of Baba Is You is defined by its constraints: which rule tiles are present, where they are placed, which objects fill the space, and how much room there is to maneuver. The player's creativity is channeled by these constraints. A level with unlimited space and every rule tile available would not be a puzzle --- it would be a sandbox. Constraints transform the sandbox into a challenge.

This is the same principle articulated in Chapter 7 (Rules, Constraints, and Freedom): limitation produces creativity. Baba Is You demonstrates this more clearly than almost any other game, because the constraints are literally visible --- you can see exactly which rule tiles the designer gave you and plan your manipulation accordingly.

Lesson 4: The Medium Is the Message

Baba Is You is not just a game about rules. It is a game that uses its rules as its primary content delivery mechanism. The medium (rule tiles as physical objects) is inseparable from the message (rules are constructs that can be questioned, rearranged, and subverted). You cannot separate the mechanic from the meaning. The mechanic is the meaning.

This is the deepest lesson: your mechanics say something. Baba Is You's mechanics say: "Rules are not laws of nature. They are choices. And choices can be changed." That message is delivered not through dialogue, not through cutscenes, not through narrative --- it is delivered through the act of pushing a word tile on a grid. The mechanic communicates the theme.

The Difficulty Curve of Understanding

Baba Is You's difficulty curve is unlike any other game. In most games, difficulty increases because the execution demands increase --- enemies hit harder, platforms are narrower, timing windows shrink. In Baba Is You, the execution is trivially easy throughout the entire game. You push tiles on a grid. A toddler could execute the inputs.

The difficulty is entirely conceptual. Each new level demands that the player reconceive what the rules can do. Early levels teach basic rule manipulation: disconnect "WALL IS STOP" and walk through walls. Mid-game levels require understanding second-order effects: making yourself into an object that has a property that interacts with another rule to create a chain reaction that produces a win condition. Late-game levels require the player to hold multiple simultaneous rule states in working memory and reason about interactions between rules that are themselves created by other rules.

This is mechanic design operating at the level of cognition. The player is not developing motor skill. They are developing conceptual flexibility --- the ability to see rules as mutable, to question assumptions, and to think several steps ahead in a system of interacting constraints. The mechanic (push) is the same in level 1 and level 200. The cognitive demand is an order of magnitude higher.

For game designers, this curve is instructive because it demonstrates that difficulty does not require execution pressure. You can make a profoundly difficult game with no time limits, no enemies, no health bars, and no reflexes. Difficulty can be entirely about understanding the system --- and that kind of difficulty, when well-calibrated, produces some of the most satisfying "aha" moments in gaming.

The Design Constraints Behind the Design

Teikari has discussed the development process in interviews and postmortems. One critical insight: the game was designed levels-first, not rules-first. Teikari did not create a complete rule vocabulary and then build levels from it. He discovered new rule combinations through experimentation, and levels were built around the specific interactions that surprised or delighted him.

This means Baba Is You's content pipeline is the reverse of most games. In a typical platformer, you design the mechanic, then design levels that test it. In Baba Is You, the designer discovers emergent interactions within the rule system, then builds levels that guide the player toward those discoveries. The game is not teaching the player mechanics --- it is teaching the player things about the system that the designer discovered after building the system.

This approach has a limitation: it does not scale with team size. Baba Is You's level design depends on a single designer's intimate knowledge of every rule interaction in the system. A team of ten level designers could not produce levels of the same quality, because the design requires understanding the full space of rule interactions, which is too large and too interconnected for anyone but the system's creator to hold in their head.

The game is a masterwork of solo development --- and a cautionary tale about the difference between systems that scale and systems that depend on a single creative vision.

The Takeaway

Baba Is You is a small game by a solo developer. It has pixel art graphics, chiptune music, and no voice acting. It won the Excellence in Design award at the Independent Games Festival, was nominated for the Game Developers Choice Award for Best Design, and is widely regarded as one of the most innovative games of the decade.

It achieved this with two verbs.

The lesson is not "make a game where rules are objects." The lesson is that mechanic design is not about the number of actions available to the player. It is about the depth of the system that responds to those actions. Two verbs, plugged into a sufficiently rich system, can produce more depth than twenty verbs plugged into a shallow one.

You probably will not make a game like Baba Is You. Almost no one will --- it is a singular creative vision that defies imitation. But the principles it demonstrates --- simplicity of input, modifiable systems, constraints as content, mechanics as meaning --- apply to every game you will ever make.

Find your verbs. Make the system deep. Let the depth do the work.