An Introduction for Indie Developers Using Preexisting Assets – What Developers Should Know About Asset Licenses

Today, it has become easier than ever for solo developers to create and distribute professional-quality games. Developers can create games on the average desktop or laptop computer without ever setting foot in a development studio, and they can release games to the public without a publisher. Even individual assets such as models, sprites, and audio files can be offered on the internet for other developers to add creative elements to. The prevalence of asset stores for buying and selling assets has made it easier than ever to use preexisting assets to create new games.

Even though this is discouraged by some critics who refer to the practice as asset flipping, developers should be careful to ensure they do not infringe on the copyrights of its creators. This includes what developers have in their own assets, how to license someone else’s assets when creating new games (whether using assets off the shelf or modifying them), the scope and limitations of those licenses, and some legal exceptions to consider.

Since the release of the Touhou 2: The Story of Eastern Wonderland NES Demake, the Drillimation Danmaku Universe has used VRoid models as a basis for designing the characters in the games. The game’s director and producer Susumu Takajima used a combination of existing textures as well as original ones to create new outfits for the characters. We’re going to use VRoid to demonstrate some of the potential issues involved when using preexisting assets for games.

Asset Reuse

Asset reuse involves taking an asset from a preexisting game and incorporating it into a new game. For example:

• Cloth textures can be recolored and/or used as part of a new texture.
• Two or more textures can be combined into a new composite image.

In many cases, asset reuse may infringe an asset creator’s exclusive rights unless the use is authorized or qualifies under copyright exceptions such as Fair Use. Since asset reuse uses preexisting assets, not only are the assets themselves implicated, but any asset that was created from two or more existing assets may require licenses from all copyright holders if the preexisting assets used to create the new asset are owned separately.

For example, assets from Drillimation Danmaku Universe games have been recycled in newer games, and have sometimes been modified. The bullet graphics from the original Chuhou Joutai have been reused in the first two Touhou Project NES Demakes and the second Chuhou Joutai game.

Interpolating

Interpolating takes part of an existing asset and incorporating it into a new asset. While this practice is often confused with asset flipping, interpolating is different because one or more parts of the asset do not incorporate everything from the existing asset.

In many cases, interpolating may infringe on the asset creator’s exclusive rights. Permission from the copyright holder may not be necessary when interpolating existing assets, regardless of how similar the new asset may be to the old asset.

For example, tiles in Touhou Kichouden ~ Mythos of Phantasmagoria 2 interpolates many tiles from Touhou Meijinka ~ Song of Divine Tempest, as well as some RPG Maker tiles.

Adaptations

An adaptation (also called a remake) is made when a pre-existing game is converted into a new game. Some adaptations seek to imitate the earlier game, while others apply different interpolations, styles, and assets to create a new version of an existing game. For example, the Touhou Project NES Demakes are all adaptations of the original games they are based on.

Asset Stores

While asset stores for engines such as Unity, GameMaker, and Unreal Engine are attractive to developers early in their careers, it is critical to understand what you are agreeing to when you use one of these services. An asset store offers assets at different price points, each with their own contractual arrangement. In many cases, the licenses can have different scopes that define what you can do with the asset, as well as related responsibilities. The lowest-priced assets have the most use restrictions, while the highest-priced assets have the fewest. Some of these common types of limitations include:

• Restrictions on what storefronts the asset can be used on (such as itch.io or Steam)
• Restrictions on how the asset can be used and what rights are involved
• Restrictions on the number of sales and/or downloads of your game
• A date on when the agreement expires.

Many of these agreements are non-exclusive, and the asset(s) can be used by multiple developers at the same time. If an exclusive agreement is offered, this means you are the only one who can use the asset for the term of the agreement and the uses specified in the agreement. Exclusive licenses are less likely to have format or use restrictions or expiration dates, but they can.

Important Considerations When Using Asset Stores

Developers should carefully read and understand any contract before agreeing to its terms. Even though asset store licenses are typically in the form of click-through agreements, reviewing these agreements carefully is just as important as reviewing other contracts or publishing deals. When using an asset store, it is important to consider whether the terms of the agreement fit your needs. Agreements that offer premium or unlimited use may still have other restrictions relevant to the uses you have in mind.

Even free assets are often subject to license terms. There may also be cases when you buy assets, but instead of obtaining full ownership, you may only be purchasing permissions to temporarily use it in limited ways. If the license term expires, you may be left with assets that you are unable to use.

In general, you should be careful to review the full agreement, and descriptions do not likely tell the whole story. Even agreements from the same asset store that use the same headline can have different restrictions when examined more closely.

It is important to know whether the asset you are considering licensing for contains other pre-existing assets or interpolations and when the sub-details need to be cleared from the original creator(s). In some cases, the creator of the asset may not have cleared the prior work’s use in the asset. Even if they have, their agreement with the original creator might not cover your use.

It is not uncommon for asset store agreements to provide the developer with rights to a certain percentage of royalties for certain uses of the game with the licensed asset, even when selling exclusive rights with the asset. This percentage ensures that the asset’s developer will share in the new game’s success if it becomes a breakout hit.

Fair Use

In some cases, certain uses of preexisting assets may be considered Fair Use under the U.S. Copyright Act and not an act of infringement. The Fair Use exception is a legal doctrine intended to promote freedom of speech by permitting the use of copyright-protected works without the need for a license in certain circumstances.

Fair Use, however, is not safe harbor. It is usually up to the courts to evaluate the exception on a case-by-case basis under four factors: This includes the purpose and character of the used asset(s), the nature of the original work, the amount and substantiality used, and the effect on the original work. The outcome of any given case is based on a fact-specific inquiry. Because works vary in size, there is no formula that determines how much of a work can be used without a license. Even disclaimers that say the use of a work is for non-infringing purposes are an internet myth and do not require proof of intent.

To learn more about the Fair Use exception, you can visit the U.S. Copyright Office’s Fair Use Index which includes a library of judicial decisions to help lawyers and non-lawyers understand which forms of expression are protected by Fair Use and which ones are not. All of the above paragraphs in this section do not constitute legal advice and you should consult your own legal counsel if you have any copyright-related questions, including whether any uses of preexisting assets conform to copyright exceptions.

Public Domain

A work is in the public domain if the copyright protection has expired or if it fails to meet the requirements of copyright protection. Public domain assets can be used freely without securing permission or a license from the asset creator(s). Please remember, however, that there are still some restrictions regarding certain assets. For example, since musical works and sound recordings are separate works, if you decide to use any preexisting recording of a public domain piece of music in a game, you must still purchase a synchronization license to use the recording in your game as the recording of the song is not public domain. Copyright law is also territorial, meaning a work could be public domain in one country, whereas it may still be protected by copyright in another.

Assets That Are Common Property

No one can prevent you from using common building blocks in assets, such as solid colors or simple geometric shapes. For example, certain lines of a video game’s source code can be reused in other games since they would not be protected by copyright, even if other elements in a game’s source code are copyrighted.

Other Concepts

Certain other copyright concepts may allow you to use preexisting assets without permission. This article only discusses a few common topics, but there are others that we may have not covered.