For Steam developers
Tools for Steam developers, from first build to release day
Build the game in a desktop engine with an AI agent, make capsule art and trailer shots from your own characters, and plan the Steamworks timeline so review never becomes the thing that moves your launch.
The short answer
Summer is a free desktop game engine for macOS and Windows that builds Windows and macOS versions of your game for Steam once the export templates are installed, plus Studio for capsule art, generated trailer shots, music and sound. It does not record gameplay to video, upload builds to Steam for you or make a Linux build. For your first few titles, Steam also asks for a 21 day wait after paying the Steam Direct fee and a Coming Soon page that is public for at least two weeks, plus a store and build review for every game.
Shipping on Steam is two projects running side by side. One is the game, which has to start cleanly on every operating system you list and implement every feature your store page claims. The other is the store presence, which has capsule art at exact sizes, screenshots, a trailer, a description, a content survey and a Coming Soon page that has to be public weeks before you can press release.
Most first time Steam developers underestimate the second project and discover Valve's fixed waiting periods late. Several of them run at the same time, so the order you start them in decides your earliest possible release date, not how fast you work in the final week.
Summer covers parts of both. The engine and its agent build and test the game, and Studio makes the capsule art, the generated shots around your gameplay and the audio. The Steamworks side, meaning the account, the fee, SteamPipe uploads and the reviews, stays yours. This page lays out that split, the Steam facts that set your schedule and where each Summer tool fits.
What it does
A desktop build for Steam
Summer builds Windows and macOS versions of a Godot 4 compatible project once the export templates are installed. Steam and itch.io both take those desktop builds.
Capsule art from your characters
Generate wide and tall key art with a screenshot of your hero as the reference, remove backgrounds for the transparent library logo, then crop every store and library size.
Generated trailer shots
Make establishing shots, logo reveals and end cards with Seedance 2.0, Veo 3.1 or Kling 3.0 in 16:9, and cut them around gameplay you capture with your own screen recorder.
Store screenshots and audio
For games built in Summer, the agent runs the game, frames a shot and captures still frames. Studio also generates music, sound effects and voice lines for the game and the trailer.
How it works
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Step 1: Start Steamworks early
Create the Steamworks account, sign the agreements and enter bank and tax details on day one. Tax verification alone can take 2 to 7 business days, and for your first few titles the 21 day wait starts only when you pay the Steam Direct fee. The Steam publishing guide walks through the account and fee.
- 2
Step 2: Build and test the desktop version
Install export templates that match your editor, export a release build for Windows and, if you list it, macOS, and test both on a machine without your development tools.
- 3
Step 3: Make the store page
Generate capsule art from your characters, export every size, capture at least five 1920 x 1080 screenshots and cut a trailer with real gameplay first. Submit the page at least seven business days before you want Coming Soon live.
- 4
Step 4: Upload with SteamPipe and submit
Upload the build as a depot with SteamPipe, set it live on the default branch, answer the content survey including AI disclosure, and plan seven business days for build review.
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Step 5: Release after both clocks run out
For your first few titles, release once 21 days have passed since the fee and the Coming Soon page has been public for two weeks. Every game also needs both reviews passed, and no trailer can still be encoding when you release.
Two ways to run it
In Studio, or from the agent you already use
In Summer Studio
Studio runs in the browser. Use the Image tab for key art and the transparent logo, the Video tab for 16:9 trailer shots and the Audio tab for music and effects. Everything downloads as a standard file, so it works for a Steam game built in any engine.
Make Steam capsule artFrom Claude, Cursor or Codex via MCP
If you build with Claude Code, Cursor or Codex, the Summer MCP lets the agent check project settings with summer_project_setting, run the game, read errors with summer_get_diagnostics and capture frames with summer_screenshot. There is no MCP tool that exports a build or uploads to Steam; export from the desktop editor and upload with SteamPipe.
Example prompt for your agent
Get this project ready for a Steam build. Check the window size, application name, version and icon settings, run the game and read the diagnostics, fix any errors, then set the window to 1920 x 1080, capture the five most readable moments with summer_screenshot, show them to me, and save the ones I pick as 1920 x 1080 PNG files in marketing/steam/screenshots.Set up the Summer MCP
| Step | What Valve says | Plan for |
|---|---|---|
| Steam Direct fee | 100 US dollars per app, not refundable, recoupable after the app earns 1,000 US dollars in adjusted gross revenue | Pay it as soon as onboarding is done |
| Wait after paying the fee | 21 days before you can release that game | Starts only when you pay |
| Tax verification | 2 to 7 business days, more documents may be requested | Do it in week one |
| Coming Soon page | Publicly visible for at least two weeks before release | Longer, to collect wishlists |
| Store page review | Typically 3 to 5 business days | Submit at least 7 business days ahead |
| Build review | Typically 3 to 5 business days | Plan at least 7 business days |
Sources: Steamworks, Onboarding
| Setting | Steam's guidance |
|---|---|
| Resolution | Highest you have, up to 1920 x 1080; 16:9 preferred, 4:3 accepted |
| Frame rate | 30 or 29.97, 60 or 59.94 fps |
| Bit rate | 5,000 Kbps or higher |
| Container and codec | .mov, .wmv or .mp4; H.264 video and AAC audio preferred |
| Audio | 44 or 48 kHz; filtered down to stereo |
| Custom poster | A frame from the video itself, 1920 x 1080 .jpg or .png |
| Placement | The first two trailers show before screenshots; the microtrailer is built from the first video |
Sources: Steamworks, Trailers
Pricing
What it costs
- Image, Nano Banana 2 Lite (1K)
- $0.07estimate
- Video clip, Seedance 2.0, 8 seconds
- $3.46estimate
- Video clip, Kling 3.0 Standard, 5 seconds
- $1.00
- Music, per minute of track
- $0.21
The engine is free to download and use. Studio generation needs a paid plan or a top-up. Steam's own fee is paid to Valve.
Prices are charged from your Summer usage balance. Generating assets needs a paid plan or a top-up: Pro is $20 a month and includes $20 of usage, and top-ups start at $10. The desktop engine itself is free to download.
See all plansExamples
Prompts that work, and what comes back
Steam jobs and the Summer tool for each one. Anything that must show real play comes from the game itself.
Capsule key art
Prompt
The knight from the reference standing on a cliff over the ruined city, dramatic rim light, empty sky top center for the logo, wide composition
What you get
A horizontal image to crop for the 920 x 430 header and 1232 x 706 main capsule.
Library hero
Prompt
Wide panoramic view of the game world, no characters, no text, main landmark centered
What you get
A text free background to crop to 3840 x 1240 with the landmark inside the centered safe area.
Trailer opening shot
Prompt
Slow aerial push over a misty valley toward a lone castle at dawn, cinematic, 16:9, 8 seconds
What you get
An establishing shot for a cinematic trailer. The gameplay beats after it come from your own capture.
Store screenshots
Prompt
Run the game, reach the first boss arena, frame the player and boss with the HUD visible and capture a 1920 x 1080 screenshot.
What you get
Real frames from the running game, for games built in Summer.
Trailer music
Prompt
Ninety seconds of rising orchestral adventure music with a clear hit at the logo reveal, no vocals
What you get
A track to cut the trailer to, generated in the Audio tab.
What build review checks
Valve's build review looks at three things. The game has to start properly on every operating system you list, every feature on the store page has to be in the current build, and any in-game transaction has to use the Steam Wallet. The first two catch most first releases.
List only the platforms you tested. Summer exports Windows and macOS builds, so a store page that also ticks Linux would promise a build you cannot make in Summer. A macOS build downloaded from the internet is blocked by Gatekeeper unless it is signed and notarized with an Apple Developer ID certificate, so budget that step or ship Windows first.
Steam Deck without a Linux build
You do not need a Linux build to be tested on Steam Deck. Valve's compatibility review tests a Linux build when one exists, and otherwise tests the Windows build running under Proton. The review changes how a game is presented on Deck, not whether it is available.
Design for it early. Valve recommends supporting 1280 x 800 or 1280 x 720, and asks that the smallest text is never below 9 pixels tall at 1280 x 800. Full controller support and no need for a manual on-screen keyboard are part of what separates Verified from Playable.
Generated shots in a Steam trailer
Valve says most Steam users are looking for gameplay and recommends that the first trailer on a store page is primarily gameplay, from the player's perspective, with the HUD visible. Summer cannot record gameplay to a video file yet, so that trailer starts with your own screen capture.
Generated shots earn their place around it, as a cold open, a pull back over the world, a logo reveal or an end card with the release date. Steam lets you label each trailer as gameplay, cinematic, teaser or a mix, so a mostly generated piece belongs in the cinematic or teaser category, below the gameplay trailer. The microtrailer Steam shows in hubs and sales is six 1 second clips taken from your first visible video, so a gameplay trailer in first place keeps that microtrailer about the game too.
Steamworks integration and AI disclosure
Achievements, cloud saves and overlay features need the Steamworks SDK in your game. For Godot 4 compatible projects the common route is GodotSteam. Summer lists it in its plugin library, but treat it like any native extension and test your exported build launched from the Steam client before you rely on it.
Steam's content survey asks you to describe AI-generated content that ships with your game and is consumed by players. Valve says it reviews that content the same way as non-AI content, including a check that the game is consistent with your marketing materials. So base capsule art on your real characters and keep generated trailer shots in the cinematic or teaser category, where they cannot be mistaken for gameplay.
Frequently asked questions
How long before I can release on Steam?
For your first few games on Steam, at least three weeks from paying the Steam Direct fee, because of the 21 day wait, and at least two weeks after your Coming Soon page goes public. Store and build reviews each take 3 to 5 business days for every game, and Valve asks you to plan seven.
How early should I publish my Coming Soon page?
Valve requires at least two weeks for your first few titles, and store page review needs at least seven business days before that. Most developers go public much earlier to collect wishlists, so submit the store page as soon as you have capsule art, screenshots and a description you are happy with.
What does Valve's build review check?
That the game starts properly on every operating system you list, that every feature on the store page is in the current build, and that any in-game transaction uses the Steam Wallet. Test on a clean machine for each platform you tick.
Does Summer upload my build to Steam?
No. You upload builds yourself with SteamPipe, from the Steamworks dashboard or steamcmd. Summer builds the game and makes the store assets.
Does my game need a Linux build for Steam Deck?
No. Summer builds Windows and macOS versions, and Valve's Steam Deck review tests the Windows build under Proton when there is no Linux build.
Can I add Steam achievements to a Summer game?
Achievements and cloud saves need the Steamworks SDK in the game, and for Godot 4 compatible projects the usual route is GodotSteam. Summer lists it in its plugin library. Treat it like any native extension and test the exported build launched from the Steam client.
Related tools and guides
Make your game. Grow your game.
Even if it is built in another engine.
Free to download for macOS (Apple silicon) and Windows.