Why Do Game Developers Secretly Despise Doors? A Deep Dive into Gaming's Most Deceptively Complex Object

To a gamer, a door is just a door. It's an entrance, an exit, a barrier, or a brief loading screen. It's a mundane object we interact with thousands of times without a second thought.

But to a game developer, a door is a Pandora's box of complexity, a source of countless bugs, and a black hole for development hours. It's a perfect example of something that seems trivial but is, in reality, a multi-faceted nightmare to implement correctly.

This notorious challenge is so well-known in the industry it has a name: "The Door Problem." Coined by game designer Liz England, it encapsulates the immense gap between the perceived simplicity of a feature and the tangled web of technical, artistic, and design challenges required to make it work.

So, why do developers, from indie studios to AAA giants, share a collective groan when the design document calls for fully functional doors? Let's open the door, so to speak, on this very topic.

Key Takeaways

1. The "Door Problem" is Deceptive: What appears to be a simple object is actually a complex system that intersects with nearly every aspect of a game, including AI, physics, animation, sound design, and level layout.
2. Technical Hurdles Abound: Doors create massive challenges for AI pathfinding (how do NPCs navigate them?), physics (what happens if they're blocked?), and multiplayer synchronization (is the door open or closed for everyone?).
3. Scope Creep & Budget Drain: Each question about a door's function-Does it lock? Can it be destroyed? Does it swing both ways?-adds significant time and cost to a project, making it a prime example of scope creep.
4. A Solved Problem for Experts: While challenging, the door problem is a known quantity. Specialized teams, like a dedicated Game Development Pod, can implement robust door systems efficiently, saving core teams from reinventing the wheel and allowing them to focus on unique gameplay innovation.

The Deception of Simplicity: What Exactly Is "The Door Problem"?

At its heart, the Door Problem is about interaction and state. A door is not a static piece of scenery like a wall or a rock.

It has multiple states: open, closed, opening, closing, locked, unlocked, and sometimes even broken or destroyed. Every single one of these states needs to be managed and communicated to the player and every other system in the game.

A developer can't just 'add a door'. They must answer a cascade of questions, each with its own set of technical requirements:

1. Interaction: How does the player open it? A button press? Automatically? By shooting it?
2. Movement: Does it swing, slide, or lift? Does it open inward, outward, or both?
3. State Logic: Can it be locked? If so, where is the key? What feedback does the player get when it's locked?
4. AI Awareness: Do enemies and friendly NPCs know how to use the door? What happens if two characters try to use it at the same time?
5. Physicality: What happens if the player or an object blocks the door from opening or closing?

Answering these questions involves programmers, animators, artists, sound designers, and level designers. Suddenly, that "simple door" has become a multi-disciplinary project-within-a-project.

The Technical Nightmare: A Multi-Disciplinary Breakdown

The true frustration with doors lies in how they violently collide with multiple, independent game systems. Getting them to play nicely together is where the real challenge begins.

🧠 AI & Pathfinding

For an Artificial Intelligence character, a wall is simple: it's an obstacle. A door, however, is a dynamic obstacle.

The AI's pathfinding algorithm needs to understand not just that the door is there, but its current state. An open door is a path, a closed door is an obstacle that can potentially become a path, and a locked door is a solid wall.

This logic can become exponentially complex. What if an enemy is chasing a player? They need to be smart enough to open the door, not just run into it. This was a significant challenge noted in games like The Witcher 3.

🏃 Animation & State Machines

The door itself needs animations for opening and closing. The player character and NPCs also need animations for interacting with it.

A character sprinting through a door should look different from one cautiously sneaking it open. Naughty Dog, the studio behind The Last of Us Part II, famously detailed the exhaustive effort required to make door interactions feel fluid and responsive, noting it was one of the longest features to implement.

This involves creating a complex state machine to handle all possible transitions smoothly.

💥 Physics & Collision

What happens when a door's swing path is obstructed by a player, an NPC, or a dropped item? The results can range from comical to game-breaking.

Does the door stop? Does it push the object? Does the physics engine have a meltdown and launch the player across the map? Developers must carefully code these interactions to prevent players from getting stuck in walls or creating physics exploits.

🔊 Sound & Visual Effects

Every state needs corresponding feedback. The creak of an old wooden door, the sci-fi whoosh of a sliding door, the desperate rattle of a locked one.

These audio cues are critical for player experience. Add visual effects like dust particles or electrical sparks, and another layer of complexity is introduced, requiring coordination between artists and programmers.

🌐 Multiplayer & Networking

In a multiplayer game, doors are the ultimate headache. The state of a single door must be perfectly synchronized across all players' computers.

If one player opens a door, everyone must see it open at the same time. If there's lag, a player might see a closed door and be blocked, while another player runs right through the open doorway.

Deciding which player's machine has the 'authority' to determine the door's state is a fundamental networking challenge that can lead to a host of bugs.

Beyond the Code: The Project Management Cascade Effect

The Door Problem isn't just a technical issue; it's a project management nightmare that demonstrates how a seemingly small feature can have a ripple effect across the entire production pipeline.

📈 Scope Creep Incarnate

A project manager sees a single line item: "Add doors to Level 3." But as we've seen, that one line explodes into dozens of tasks for multiple departments.

This is classic scope creep. A QA tester for The Witcher 3: Wild Hunt noted that a single door meant to unlock after a boss fight had 12 different scenarios that could cause it to fail, trapping the player.

The eventual fix? They just left the door unlocked.

🐞 A Gateway to Bugs

Because doors touch so many systems, they are a fertile breeding ground for bugs. A change in the physics engine can break doors.

An update to the AI can make NPCs forget how to use them. A quest scripting error could accidentally open every single door in the game, including cosmetic ones not meant to lead anywhere, as once happened in The Witcher 3.

This makes testing a time-consuming and often frustrating process.

🎨 Level & Game Design Constraints

Functionally, doors are also a powerful tool for level designers. They control pacing, create suspense, and can be used to hide level streaming, loading new areas while the player is occupied by the door-opening animation.

However, this also means the level's flow is entirely dependent on these complex objects working perfectly. Some games, like many in the Assassin's Creed series, solve this by simply omitting functional doors altogether, using open archways or short loading screens instead.

Taming the Beast: A Structured Approach to the Door Problem

While daunting, the Door Problem is solvable. Success requires acknowledging the complexity upfront and creating a clear, robust framework.

An effective strategy involves treating doors as a core system, not a simple asset.

Here is a checklist that development teams should consider:

This is precisely where an experienced partner can be invaluable. At Developers.dev, our specialized Game Development PODs don't start from scratch.

We have pre-built frameworks and a deep well of experience in solving these foundational challenges. By outsourcing complex but common problems like doors, your core team is free to focus on what makes your game truly special: the story, the mechanics, and the player experience.

2025 Update: Are Modern Engines Making Doors Easier?

Modern game engines like Unreal Engine 5 and Unity have certainly streamlined parts of the process. With advanced features like Unreal's Chaos physics engine and sophisticated animation blending tools, some of the lower-level technical work is more manageable.

Asset marketplaces also offer pre-built door systems that can provide a starting point for developers.

However, the fundamental challenge remains. These tools don't solve the core design problem. They don't decide how your specific game's AI should interact with a door, or how to resolve a conflict when a player and an NPC try to use it simultaneously.

The complexity has moved from raw code to systems integration. While the tools are better, the systemic nature of the Door Problem persists. It's a timeless example of how in game development, nothing is ever as simple as it looks.

Conclusion: More Than Just a Door

The infamous Door Problem serves as a powerful lesson for anyone involved in software or game development. It's a reminder that the simplest-looking features can hide immense complexity.

It highlights the deeply interconnected nature of game systems, where a change in one area can have unforeseen consequences in another. For developers, it's a source of frustration, but also a testament to the incredible amount of unseen work and ingenuity that goes into creating the seamless virtual worlds that players enjoy.

Understanding this complexity is key to effective project planning and resource allocation. Instead of letting your most talented developers get bogged down by solved problems, you can leverage specialized teams to build these foundational systems efficiently and reliably.

This allows your studio to focus on innovation and deliver a polished, bug-free experience on time and within budget.

This article has been reviewed by the Developers.dev CIS Expert Team, a collective of certified professionals in cloud solutions, software engineering, and enterprise architecture.

Our experts are dedicated to providing practical, future-ready solutions based on years of industry experience and a commitment to excellence, backed by certifications like CMMI Level 5, SOC 2, and ISO 27001.

Frequently Asked Questions

What is the 'door problem' in game development?

The 'door problem' is an industry term for the unexpected and disproportionate amount of difficulty involved in implementing a seemingly simple feature, like a door, into a video game.

It's used as an analogy for how features that seem trivial on the surface require complex interactions between multiple game systems, including AI, physics, animation, and level design, leading to significant development time and potential for bugs.

Why are doors so hard to program in games?

Doors are hard to program because they are not static objects. They have multiple states (open, closed, locked) that must be managed and synchronized.

They must interact intelligently with numerous systems:

1. AI: NPCs need to understand how to navigate through them.
2. Physics: The game must handle collisions and obstructions correctly.
3. Animation: Both the door and the characters need believable animations for interaction.
4. Networking: In multiplayer games, the door's state must be consistent for all players.

The combination of these requirements creates a high potential for bugs and complex coding challenges.

Are there games that are famous for their doors?

Yes, but often for the effort involved. The Last of Us Part II is frequently cited, with co-game director Kurt Margenau explaining the immense work that went into their fluid and dynamic door systems.

Conversely, games like The Witcher 3 are known for the humorous and game-breaking bugs their doors sometimes caused. Many other games, like the Assassin's Creed series, are notable for avoiding the problem by designing levels with fewer functional, swinging doors.

How can a game studio avoid getting bogged down by problems like doors?

The best approach is to recognize the complexity upfront and plan accordingly. This includes:

1. Standardization: Create a single, robust, and reusable door system or 'prefab' that can be used throughout the game.
2. Clear Design: Make firm decisions early on about how doors will function to prevent feature creep.
3. Dedicated Resources: Assign developers to own the system and become experts on it.
4. Leveraging Expertise: For many studios, the most efficient solution is to partner with a specialized team, such as a Game Development Pod, that has already solved these problems and can implement a reliable system quickly, freeing up the core team to focus on unique gameplay features.

   
   

   Stop Wasting Development Cycles on Solved Problems.

   Your team's talent is best spent on creating unforgettable gameplay, not wrestling with the notorious 'Door Problem'.

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