If Mac game developers miss these settings, their brand new game for Apple Silicon will be listed as unplayable on anything after macOS 10.15 Catalina. Here's how to tell Steam that your game is compatible, and where the flags are.

Valve Software's gaming storefront, Steam, is the biggest of its kind when it comes to PC and Mac gaming. It is essential for any game developer targeting those platforms to put a build on Steam, due to the sheer size of its audience.

However, while Steam is relatively simple for gamers to use, the back-end is considerably more complex. For a developer starting out, there are many things that can be missed when putting their game onto Steam for the first time.

Indeed, with one specific set of tick-boxes, they can actually cause some big problems if left unchecked by Mac developers.

Warning boxes

Like any good software retailer, Steam has sections that detail what platforms a game will work on. This is all to help consumers find games that will run great on their PC or Mac.

At the same time, Steam will aggressively warn users if a game won't work on a specific system.

In the case of Mac games, you may run into a pair of outlined warning boxes near the top of the store listing. One is far more damaging to Mac gaming sales than the other.

Two dark blue notification bars stating the product is incompatible with macOS Intel systems and macOS 10.15 Catalina or later, each ending with a clickable

Two Steam page notices Mac developers have to look out for.

The worst orange warning box is the one that states, "Notice: This product is not compatible with macOS 10.15 Catalina or above." This is not good because it tells consumers it won't run on modern Macs at all, including Apple Silicon.

This is in part due to macOS Catalina being the first to drop support for 32-bit apps. As a consequence, in October 2019, Steam required all new macOS applications entering its store to be 64-bit and notarized by Apple.

By saying the game is not compatible with macOS Catalina, Steam is saying the game won't run on any Macs using macOS Catalina or later.

The other warning notice is less damaging: "Notice: This product is not compatible with macOS systems using Intel processors."

Again, this is Steam telling consumers that your game won't work on Intel Macs at all. Most developers will have to live with it, since they may not be building for Intel Macs at all, just Apple Silicon.

This is much less of a problem, since it's a problem that only really applies to the browser-based version of Steam. Users on Apple Silicon using the Steam client don't see the message.

Background tickboxes

The fix for game developers is mundane. It's simply a case of going into Steamworks, Valve's backend for the store, and ensuring some boxes are ticked:

  • Open Steamworks with your developer account.
  • From the Dashboard, select the relevant game app, then Edit Steamworks Settings.
  • Alternatively, from the Dashboard, select Apps & Packages in the menu, then All Applications. Select the Steamworks Admin link next to the relevant game.
  • In the Application section, under Supported Operating Systems, make sure that macOS is checked, as well as the Apple Silicon Binaries Included and 64-bit (Intel) Binaries Included options, if applicable.
  • Make sure App Bundles Are Notarized is also ticked.
  • Hit Save.
  • Select the Publish tab. Click Prepare for Publishing, then Publish to Steam.
  • Since it is a change viewable by the public, you also need to complete an additional confirmation. Type "STEAMWORKS" into the text box as required, optionally add some internal change notes, then click Really Publish.

Valve's support teams do not analyze the executable you supply when it comes to the store page listing. They do when you're uploading a build or a demo for distribution, but not when making the store page itself.

Dark interface section titled Supported Operating Systems, showing selectable options for Windows, macOS, Linux, and Android with various macOS distribution checkboxes and a Save button at the bottom

Checkboxes in Steam that Mac game developers really should tick.

That means you need to get the tickboxes right, since Valve is not doing it for you.

What those four tickboxes mean:

  • macOS: Confirms the game is on macOS.
  • 64-Bit (Intel) Binaries Included: Indicates you have either included an Intel-specific Mac build or you're using a universal binary. This will run on Intel Macs.
  • Apple Silicon Binaries Included: The same thing, but for Apple Silicon
  • App Bundles Are Notarized: You have gone through the notarization process with Apple, and that's the build you're uploading to Steam.

Once set up correctly, the public will see a store page that won't have the dreaded and confusing macOS Catalina warning. But they may still see the Intel Mac notice if they're using the website.

It's already tough to market a game on Steam, and to convince people to buy. Do this, and you won't have Steam working against you either.