Your game's art, models or music turned up in someone else's game. How to prove it and get it removed.

You recognize it before you can explain it. A character you drew, a model you spent a week on, a track you wrote at two in the morning, sitting inside a game with someone else's name on it.

A game we shipped was extracted, rebuilt and resold, so we know the particular feeling of seeing your own work used as raw material. This page is for the case where the other game is not a copy of yours. It is a different game built partly from your pieces: your art, models, animations, sound or music. The same thing happens when someone packages your assets and sells them on an asset store. It covers how to rule out the innocent explanations, how to check that you actually own what you are claiming, how to prove copying one asset at a time, where to send notices, and what tends to happen next. It is not legal advice, and the places where a lawyer is worth paying are marked.

1. First, rule out a shared source

This step protects you. A copyright notice is a statement made under penalty of perjury, and the most common way to get one wrong is to claim something you only licensed. Before you go further, answer these honestly for each asset you found.

• Did it come from an asset store? Store licenses are not exclusive. The Unity Asset Store's license, for example, is a "non-exclusive, legally binding end user license agreement", so every buyer of a pack can ship the same model. If you bought it, they may have too. That is not copying from you.
• Did you start from something you licensed? If your character was built on a purchased base mesh, a free texture library or a sound pack, only what you added is yours. The Copyright Act says the copyright in a derivative work extends only to the material contributed by the author, not the material it was built on. The other game may have started from the same base.
• Did a contractor make it? A freelancer who sold you an asset may have sold it again, or reused parts of it. If they still own it (section 2), that resale may even be lawful.
• Did you allow it? A modding policy, a press kit, a jam license or a free sample can all grant permission. Read what you published.
• Could it have reached them through a mod or a third party? In 2016, the developer of Starsector found art in another game on Steam that, as GamingOnLinux reported, came from a mod of Starsector that used the original game's assets. The other developer said the art came from elsewhere. Copying through an intermediary is still copying, but it changes who you are dealing with and how you write to them.

If the answer to any of these is yes, the asset may still be infringing, but the case is about a license or a contract, not simple copying. Talk to a lawyer before you file a notice about it.

2. Confirm that you own what you are claiming

The person entitled to sue is the "legal or beneficial owner of an exclusive right" under the copyright. Store forms ask the same question in a different way: you must state that you own the work or are authorized to act for the owner. So before anything else, work out who owns each asset you are about to claim.

• You made it yourself. Copyright "vests initially in the author". If you made it and never signed it away, it is yours. If your company sells the game, something in writing should say how the company got the rights.
• An employee made it as part of the job. It is a work made for hire, and the employer is the author and owner. The Copyright Office's Circular 30 lists the factors courts use to decide who counts as an employee: who supplied the tools, how the person was paid, whether taxes were withheld, how long the relationship lasted.
• A freelancer made it. This is where most small studios are exposed. A commissioned work is made for hire only if four things are all true: it falls into one of nine listed categories, there is a written agreement, in it the parties "expressly agree that the work is to be considered a work made for hire", and everyone signed it. Otherwise the freelancer is the author.
• A freelancer assigned it to you. An assignment works for any kind of work, but a transfer of copyright is not valid unless it is "in writing and signed" by the person giving it up. A paid invoice, an email saying "it's yours" with no signature, or a chat message is weak ground.
• You licensed it. You can use it. You generally cannot enforce it, unless your license is exclusive. The owner can.

One of the nine categories for commissioned work is a part of a "motion picture or other audiovisual work". Whether a particular game asset falls into it is a question for a lawyer. A signed assignment avoids the question entirely, which is one reason many studio contracts include both.

If a contributor still owns it

You have two honest options. Ask the contributor to send the notice themselves, as the owner. Or get a signed written assignment now. The statute lets an owner sue only for infringement "committed while he or she is the owner", so an assignment made after the copying should expressly include the right to pursue past infringement. That wording is worth a lawyer's hour. Most contributors are glad to help. It was their work that was taken, too.

Music and sound

Composers often license music to a game rather than assigning it. If the composer kept ownership, the composer is the one who files. Sound effects built from a commercial library carry the same shared-source problem as art packs. YouTube's automated matching system is limited to owners who "have the exclusive rights to the material", which rules out library sounds and most licensed tracks.

3. Prove it, one asset at a time

A notice that says "they stole our art" is easy to dispute. A notice that lists twelve assets, each with your original and their version side by side, is not. Build the comparison before you contact anyone, because a listing can change once the seller knows.

Capture their side

• The store page address, developer and publisher names, price and release date, saved with a date.
• Screenshots or video of each asset as it appears in their trailer, store images and game. A copy of their game, bought or downloaded the normal way, lets you record it in play.
• Where the same asset appears more than once (a store image, a trailer, a level), record every place.

Capture your side

• Your original files, with their history. Layered source files, project files, the version-control commit that added the asset, and exports from earlier versions all show that the work existed before theirs and that it grew in your hands.
• Dated public appearances. A devlog post, a social media post, a store page screenshot, a trailer upload or a demo release date. A public record with a date that you do not control is the strongest kind.
• The release date of the build that first contained the asset.

Point to what nobody reproduces by chance

Two artists drawing a knight will draw similar knights. That is not copying. What shows copying is the detail that only exists because of how you made it: the same mistake in a texture, the same odd number of frames in an animation, the same color off by one shade, the same unused corner of a sprite sheet, a note held one beat too long. Mark these on the side-by-side images and name them in a sentence each.

A modified copy is still a copy. When Activision had the game Orion removed from Steam in 2016 over three weapon models, one commenter quoted by MCV said the models were "literally the same models, only dismantled and spread out a bit". The developer disputed the claim, and the report does not say how it ended. The point is the shape of the argument: rearranging, recoloring or rescaling an asset does not make it a new one, and your comparison should show the pieces lining up.

Make one folder per asset, with your original, their version, the comparison image and a short note. It becomes your notice, your answer to any counter-notice, and your file for a lawyer if it goes further. The first page in this series covers preserving a store listing in more detail.

4. Decide whether to write to them first

This section is our advice. You do not have to contact the other developer before sending a notice. Sometimes it is worth it.

• Write first when a few assets are involved, the developer looks like a small team acting in good faith, and they may have bought your work from someone who had no right to sell it. A short, factual message with the comparison images and a date to reply by often gets the assets replaced without anyone losing a store page.
• Go straight to the store when the copying is extensive, the developer has ignored or denied clear evidence, the game is earning money from your work now, or you have reason to think they will alter the evidence.

Either way, keep it in writing, keep it calm, and do not threaten anything you are not prepared to do. Ask for something specific: remove these assets by this date, or tell you where they came from.

5. Where to send notices

Send a notice to each place that carries the assets. Every route below is the platform's own, as of October 2026.

What changes in the notice

The notice needs the same elements as any U.S. copyright notice, and the first page in this series walks through all six. Two things are different when the copy is partial.

• Name every asset. The law allows a notice covering many works at one site to give "a representative list of such works". In practice, list every asset you can and attach or link the comparison for each. The reviewer needs to see the match without opening your game.
• Say what you are not claiming. If their game uses a store pack that you also used, say that those assets are not part of your notice. It shows care, and it stops a counter-notice from winning on the parts you never claimed.

6. What happens next

A store usually removes the whole listing, not the single asset. That is how notice systems work: the store does not edit the other developer's game. In the Orion case, MCV reported the game "will be offline for a period of 10 days", during a Steam sale. That is a large consequence for a dispute over a few models, which is the best reason to be sure.

From there, one of three things usually happens.

1. They replace the assets. Many developers swap in new art and ask the store to restore the listing. If that is all you want, you can tell them, in writing, that you will confirm it once the assets are gone.
2. They do nothing, and the listing stays down.
3. They file a counter-notice. Under U.S. law the store can restore the listing in 10 to 14 business days unless you file a lawsuit. The page on counter-notices explains that clock in calendar days and what the other side has to swear to.

Be careful with the claim itself. Someone who knowingly misrepresents infringement in a notice can be liable for the harm it causes under section 512(f). An honest mistake is not the same as a knowing one. Section 1 exists to keep you clear of both.

If they counter and you want to go further

A U.S. lawsuit over a work first published in the United States generally needs a registration, or a refused application, before it can be filed. Statutory damages and attorney's fees depend on registering in time. Assets released in a game are usually covered by the game's registration if you owned them and claimed them. The registration guide covers what the application includes and how to exclude what you licensed. For a dispute too small for federal court, the Copyright Claims Board is a cheaper route. This is the point to talk to a lawyer.

7. If your assets are being sold as a pack

Sometimes the assets are not in a game at all. They are listed on an asset marketplace as someone else's pack. This is worse than a single game, because every sale puts your work into another project, and every buyer believes they hold a license.

• Go to the marketplace first. Removing the pack stops new copies. Use the routes in section 5.
• Treat buyers as people who were deceived. A license from someone who did not own the asset gives the buyer nothing, but they paid in good faith. If you find your assets in games built from the pack, a friendly message usually works better than a notice.
• Keep a list. Record the pack's name, seller, listing address and any games you find it in. If the seller relists under another name, the list shows a pattern. Unity's policy says it may terminate accounts that "repeatedly infringe".

8. Before it happens again

None of this stops someone from taking your art. What it does is turn the next case from a week of reconstruction into an afternoon. This is our advice.

• Get signatures. Every contributor who makes art, models, animation, sound or music signs a written agreement that assigns the copyright to you or your company. Do it before the work starts. Check old contributors now, while everyone is on good terms.
• Keep a ledger of what you did not make. One file listing every licensed pack, library and font, with where it came from and its license. It answers section 1 in minutes, and it lets you exclude licensed material from a registration.
• Keep source and history. Version control for art as well as code, and layered source files kept after export. Your history is your proof.
• Show work in public with dates. Devlogs, progress posts and trailers are marketing. They are also dated records that you do not control, which is what makes them strong evidence.
• Register the game. A registration made in time keeps statutory damages and fees available. It is also the strongest evidence you can attach to a notice.

Common questions

Someone used my game's sprites in their game. Is that copyright infringement?

If you own the sprites and they copied them without permission, usually yes. Check first that the sprites did not come from a shared pack or a contributor who still owns them.

They changed the colors and proportions. Is it still mine?

Changes do not turn a copy into a new work. What matters is whether your asset was copied. Show the details that line up underneath the changes.

A freelancer made the art and we never signed anything. Can I still file?

Probably not as the owner. Without a signed written agreement, the freelancer usually owns it. Ask them to file, or get a signed assignment that includes the right to pursue past infringement.

The asset is in their game, and it is in a store pack I also bought. What can I do?

Usually nothing. A store license is non-exclusive, so anyone who bought the pack can use it. Only what you added to the pack is yours.

Will Steam remove just the stolen asset?

Stores generally remove the listing, not part of the game. The developer then replaces the asset, files a counter-notice, or stays down.

Someone is selling my game's assets on the Unity Asset Store or Fab. Where do I report it?

Unity takes notices through the web form on its intellectual property and takedown policy page. Epic takes notices for Fab through its intellectual property infringement page.

Do I need to register my copyright to send a notice?

No. You need it before filing most U.S. lawsuits, and registering in time affects what you can recover.

Should I contact the other developer before filing?

It is your choice. A short, factual message often gets assets replaced when the copying is small and the developer may not have known. Go straight to the store when the copying is extensive or clearly deliberate.

Can I use YouTube's matching system to find my music in other games?

Only if you hold exclusive rights to the music. Tracks built from libraries, and music you licensed from a composer who kept ownership, generally do not qualify.

This page describes sections 103, 201, 204, 501 and 512 of title 17 of the U.S. Code, the U.S. Copyright Office's Circular 30, the Unity Asset Store end user license agreement, Unity's intellectual property and takedown policy and its help article on flagging assets, Epic's help article on stolen Fab work, Valve's notice form, itch.io's terms of service and YouTube's Content ID eligibility page, as read on 15 October 2026. The Starsector and Orion accounts are quoted from the linked GamingOnLinux and MCV reports. The statements that freelancers sometimes resell work, that stores remove listings rather than single assets, and that developers often replace assets once told are general description without a linked source. The sections on writing first, asset packs and the next release are our own advice. It is general information, not legal advice about your situation.