Frequently asked questions

A community-developed 64-bit engine mod for The Sims 3. We’re building a new engine around the content and original gameplay code from your installed game.

The engine loads resources, draws the world and provides systems that the gameplay code relies on. Here’s how the pieces fit together. It’s still in pre-alpha.

No. OpenTS3 will not run standalone. You need your own legally acquired, installed PC copy of The Sims 3. You must also own and install any packs or paid content you use.

OpenTS3 won’t include the original game files or unlock content you don’t own. We do not endorse piracy. Game requirements and where to buy →

No. OpenTS3 is an unofficial community project, developed independently of Electronic Arts and Maxis.

This website is not endorsed by or affiliated with EA or its licensors. The Sims 3 and its content belong to their respective rights holders.

OpenTS3 will always be free. No paid builds, subscriptions or paid playtest places. The original game and any packs you want to use are separate purchases.

There’s no public download yet, and no announced release date. This website will link to the official download when it’s ready.

Early alpha builds roll out features to playtesters in stages. The full public release is planned to include the complete game and full expansion and stuff-pack compatibility. Development videos show work in progress. For what works and what still needs attention, see the roadmap.

Private playtesting is underway. We plan to invite more people as builds are ready for wider testing. Announcements and requirements will be shared in JJs Game Lab on Discord.

Applications aren’t open on this website. Joining Discord or sending a message doesn’t reserve a place, and tipping won’t move you up a queue.

Windows x64 is the current playtest focus. Vulkan is the main renderer, and the runtime has moved to .NET 10. The Windows player package bundles the runtime and its launcher checks your installation and graphics driver; players don’t need the development SDK. Wider hardware and game-version coverage are still being tested.

Substantial Pets, Seasons and Late Night gameplay is working in private playtests, including Appaloosa Plains and Bridgeport. Riverview also loads. Full expansion and stuff-pack compatibility remains the release target, with extensive QA still to do. Linux and macOS compatibility work and testing are ongoing; this is not a guarantee for every platform or GPU.

Developers are playing The Sims 3 in the new 64-bit engine: cars, stairs, relationships, birth, aging and death work in current private playtests. Most Build/Buy tools and substantial Pets, Seasons and Late Night gameplay are also running.

The focus has shifted to performance, optimization, shaders, audio and broad QA. There are still broken details and a lot of combinations to test. Working gameplay is not the same as exhaustive compatibility or a finished public release. See the current roadmap →

Mods and custom content load in current private builds. The launcher supports drag-and-drop package mods, supported Sims3Pack objects, CAS parts and patterns, saved Sims and saves. Mods are off by default until you enable them.

Compatibility still depends on the exact mod and OpenTS3 build. Lot and household Sims3Pack imports and Store objects needing their own scripts remain incomplete. The optional Store-content path loads owned installed content, including Riverview buildings; it does not unlock purchases or guarantee every Store item works.

Original saves and worlds load in tested cases, and save/reload checks have expanded. OpenTS3 now defaults to Documents/OpenTS3/Saves rather than the original game’s save folder. The launcher also accepts dragged-in save copies. Broad original-save compatibility, long sessions and complete saved-world transitions are still being checked.

Keep your original saves backed up. Follow the instructions supplied with any future playtest, and don’t use your only copy of a household you care about for testing.

Better responsiveness and stability are goals. A 64-bit engine provides more memory headroom, but it doesn’t automatically make everything faster or fix every crash.

We need repeatable measurements during actual gameplay before making performance comparisons. The performance section of the roadmap tracks that work.

We use AI tools for coding, debugging and reviewing changes. OpenTS3 is building the engine and the connections it needs to work with the original gameplay code and content from your installation.

People direct the work, test builds and refine the code. An AI saying “fixed” is a reason to test it, not a reason to call it finished.

JJ leads the project, with eight other C# developers on the team. We work together on the engine, compatibility, debugging and testing. AI tools assist with development; people direct the work, review changes and test the game. Meet JJ or read about the development process.

OpenTS3 will be open source. The repository is private while development is underway, and there’s no announced date for the public source release yet.

The repository currently uses GPLv3. Source and dependency reviews must be completed before publication. That release will cover OpenTS3’s own code; EA’s original game files won’t be included.

The roadmap records progress and known issues. JJs Game Lab on YouTube has development videos, and Discord is where project discussion and future playtest announcements happen.

The featured video on the homepage follows the OpenTS3 playlist.

That’s the plan for later: a free directory linking to creators’ mod pages, compatibility reports and a community forum. These features aren’t available yet.

Downloads will stay with their creators; we won’t host or reupload their files. Read the plans for the community hub →