Retrobator is a new NES emulator available on Itch.io (and coming soon to Steam.)

See the Downloads section for the latest Starter Package.

Features

• Timeline – Go back in time by seconds, minutes, or hours to watch a replay or restart gameplay from any point.
• AutoMap – Reveals traversed areas of the game when zoomed out and “extends” the game on wider screens.
• Sprite Replay – Animates gameplay history on top of the AutoMap.
• Backdrops – Give your games custom backdrops via color keying.
• Motion Interpolation – Provides smoother scrolling and sprite movement by utilizing frame insertion.
• AI Assistant – Hook up an AI agent to Retrobator for voice control and interactivity. OpenAI API credit required.
• Pressure-sensitive fast-forward/rewind/slow-motion via gamepad trigger buttons.
• High-resolution unmixed audio waveforms with adjustable octaves.
• Input lag mitigation, CRT TV filter, trail effect, save states, cheats, and more.

Timeline

The Timeline records gameplay history as you play, allowing you to seek backward and forward as if you were navigating a video. You can watch a replay or even start over from any point in the timeline.

The Timeline can be traversed using a mouse, keyboard, or gamepad trigger buttons.

Note: The maximum timeline size is configurable and currently consumes around 150 MB of disk space per hour per game.

AutoMap

As you play, Retrobator will stitch together “maps” of the in-game areas that you’ve traversed. At any time, you can zoom out from your current in-game location and pan around the current map.

To zoom: Move the mouse wheel or the right gamepad stick.
To pan: Hold and drag the right mouse button or move the left gamepad stick.

Note: AutoMap will make a modest effort to connect maps together when warping around a game. This is an error-prone process with room for improvement. If you find that AutoMap performs particularly poorly for a specific game, please let us know in our Issues. You can also disable AutoMap in the corresponding menu.

Sprite Replay

As you zoom and pan around a map, Retrobator will show recent gameplay loops in the surrounding map areas, letting you relive your past failures achievements again and again.

The frequency and duration of these replay loops are configurable in the AutoMap menu.

Trail Effect

This feature adds an afterimage effect behind moving sprites.

Enable and configure trail effects in the AutoMap menu.

Backdrops

For a given game, you can display custom wallpaper images that will show through the game screen wherever color keys have been defined (see Color Keys).

Choose a backdrop image from multiple sources:

• Drag and drop an image file into Retrobator.
• Download an image from a web link.
• Generate an image from a prompt (OpenAI API account required).

Defining Per-Tile Color Keys

To see the Backdrops, you must tell Retrobator which tiles and colors to hide, resulting in sort of green-screen effect.

While the Backdrops menu is open, select individual game tiles to change their color keys.

Note: Tile color key settings can be exported; the Starter Pack predefines transparent colors for some games.

Transparent Window

Note: Experimental. May not work on some systems.

With this option enabled, anything that is behind the Retrobator window (a desktop background, video, or other content) will be shown as a backdrop.
For instance, you can watch your stonks go up in the background while you play video games.

Motion Interpolation

By default, Retrobator will track and interpolate game tiles to create smoother scrolling and sprite movement between frames.

Motion interpolation is most noticeable at slow-motion speeds. At normal game speed (60 fps for most games, with notable exceptions), a monitor with a refresh rate higher than 60 Hz is required to notice the effect.

To slow things down, lightly depress the gamepad triggers or hold down the slow-motion key.

Palettes

In the Colors menu, you can change the system-wide color palette or modify individual colors.

AI Assistant

If enabled, Retrobator allows you to interact with a virtual assistant powered by generative AI.

Note: AI Assistant is an experimental feature that requires an OpenAI API account with added credit. Additional AI providers may be supported in the future.

Use cases:

• Ask your AI assistant (using voice or text) to do various things for you: open games, enable cheats, create backdrops, etc.
• Converse, banter, and have it react when in-game events occur.
• Customize its personality.

Note: Unless asked, the AI Assistant does not see usually see what’s happening on the screen. To provide better context, see events.

Note 2: See the Q&A section for some API cost-saving tips.

Setup

First, create an OpenAI API key:

1. Create an OpenAI API developer platform account on their site (platform.openai.com).
2. Add some Pay as you go credit (currently in the settings under Billing).
3. In Dashboard → API Keys, create a new secret key, and copy the key value to the clipboard.

In Retrobator, open the Assistant menu, and under AI Provider, paste the key into the “Key” field. At this point, the AI assistant is ready to use.

To chat with the AI assistant, hold the push-to-talk button (the Tab key or left shoulder gamepad button) or type your message into the message window (toggle with grave accent '`').

Enabling Reactions

To enable assistant reactions to in-game events, the following conditions must be met:

• At least one Event has been labeled for the current game. For immediate reaction, the event must be configured with Immediate notification.
• The AI persona you select has the Reacts to Events box checked.

Events

For each game, you can identify and label gameplay “events” for Retrobator to track and count. These events show as markers on the Timeline. Events are optionally used to inform the AI Assistant and give it a chance to respond.

Note: Events are also exportable. Basic events for some games are provided in the Starter Pack.

Trackable events are typically simple in nature and result in a visual or auditory cue. Examples:

✅ “Player died”
✅ “Game over”
✅ “Player finished game”

Likely untrackable:

❌ “Player is shooting”
❌ “Player died from X”
❌ “Player lost X health”

Look for more event-enabled features in the future!

Labeling Events

To define an event, you must provide real examples of the event in order to train Retrobator on how to identify it.

1. Play the game until you have at least two instances of the event in your Timeline.
2. In the Events window, hit the “+” button to create a new event.
3. For each and every instance in the timeline, navigate to the frame / nearby frame at which the event took place.
   (Next to Instances, hit the + button to add the current frame as a training instance.)
4. Press Train to analyze the instances and create the event.
   If training fails:
   
   1. Ensure that all instances of the event in the training range have been added to the training set.
   2. (Optional) Adjust the leeway to include more training frames around each instance.
5. Test the event by playing the game. When the event occurs, ensure that it shows up in the timeline.
   If an event was not detected, add the instance to the instance list, and train again.
   When a false positive is detected, remove it from the instance list, and train again if needed.

Packages

The package system makes it easy to import and export premade settings files (.b8r extension) from/to other Retrobator users.

Currently, the following items can be imported or exported from Retrobator:

• Labelled Events
• Tile Color Keys

To import or export a package, see the Import/Export menu.

Downloads

⬇️ Starter Pack (Updated: May 7, 2025)

The Starter Pack contains basic event definitions and color key settings for 30+ games.
To install, download the file above and import it from within Retrobator.

Support

To report an issue, see Issues. Also see Discussions.

Q&A

What are the supported platforms?

Retrobator runs on Windows 10+ (x64), with other platforms tentatively planned.

Which games are compatible?

Retrobator will run most NES/Famicom-compatible games, with a few notable exceptions. If you want a particular game to be supported, let us know here.

Where do I find games to use with Retrobator?

Note that Retrobator does not include any games.

Retrobator only runs games that are in digital form (with a ".nes" file extension.) You can find indie NES-compatible games on Itch.io.

Digital backups of your physical game cartridges can be made using INLRetro and RetroBlaster hardware.

Will Retrobator be offered on Steam?

Valve require that external services (such as OpenAI) be connected via the their subscriptions or microtransaction systems. Because this would increase the cost of these services to you, we’ve decided forego a Steam release until we can bundle an offline model with Retroabor.

How do I minimize AI costs?

Ways of reducing AI API costs (see the Assistant menu):

• Select a non-'realtime' model.
• Select a 'mini' model.
• Disable 'Responds with speech'.
• Disable unneeded AI tools.

As of this writing, you can look at platform.openai.com/usage to view usage costs.

Does Retrobator support modding?

A modding/scripting system is in the works and may see a release in the future.

Who are you?

The team consists of one highly motivated, insane man.

What’s next?

We’ve got more features in the pipeline; If there is something you’d like to see, drop it in our Discussions.

Credits

Demonstrated games:

Pinky Xmas - Axbakk Games
Pinky - Axbakk Games
Sam's Journey - Knights of Bytes
Flea!2 - Lowtek Games
neMULEsis - John Vanderhoef
Blade Buster - HLC Project

Disclaimers

Retrobator is not affiliated with or endorsed by Nintendo.