Epic Games says that PC crossplay must be enabled for all multiplayer games in its store. This is due to the anger over Space Marine 2 installing Epic Online Services automatically.

Warhammer 40,000 Space Marine 2 has a great start, but there are some players who are not happy with one aspect: the game's use Epic Online Services. This allows cross-play between Epic and Steam, as well as friends list synchronization. Space Marine 2 publisher Focus Entertainment clarified that players do not have to link their Steam and Epic accounts to play the title. However, Epic has told Eurogamer recently that crossplay support is required for any multiplayer game sold on its store.

Epic's representative said that "Crossplay across all PC storefronts" is a requirement for all multiplayer games. This ensures that players and their friends can play together, wherever they buy their games. "Developers can choose any solution that meets this requirement, such as Epic Online Services. This may require a second installation to enable Social Overlay on PC (friends lists and cross-platform invitations).

You don't have to use Epic Online Services to play your multiplayer game. However, you must follow the steps Epic Online Services takes to get on Epic's Store.

SteamDB lists 944 games that use the client, including Satisfactory, Palworld, Elden Ring, Disco Elysium, Football Manager 2021, Jusant, Armored Core 4, Hogwarts Legacy, and Payday 2. SteamDB lists 944 titles that use the client. These include Satisfactory and Palworld. Also included are Elden Ring, Disco Elysium Football Manager 2021 Jusant, Armored Core 4 Hogwarts, Payday 2, and Payday 2.

Epic's policy on PC storefront crossplay wasn't new when it introduced self-publishing tools to the Epic Games Store in 2023. It's also worth noting that Epic Online Services is completely separate from Epic's decidedly poor launcher. Heroic is a great alternative if you're having problems with Epic.

In response to a negative review on Steam by a Space Marine 2 Developer, EOS "isn't a mandatory install." You can uninstall it via the Windows Add/Remove Software menu. However, you will not be able to play with other players outside of Steam.