Update: Valve has posted an update that details how developers can implement Easy Anti-Cheat into their Steam Deck games, and has confirmed it doesn't require Epic's Online Services.
Many PC gamers won’t be strangers to Epic’s Easy Anti-Cheat (EAC) service, designed to detect unfair play in games. It recently became free, which means it’s about to be implemented in more games than ever before.
Valve wants as many games as possible working on the Steam Deck, and the implementation of anti-cheat software seems to be a major obstacle to this goal. Steam Deck uses a compatibility layer called Proton that allows Windows games to work on the Linux platform. A few months back, Epic announced that Easy Anti-Cheat would work with Proton, and could be enabled by developers with "a few clicks" which was good news given the popularity. Now we are learning that this might not be the case.
According to a developer of Vermintide 2 (via GamingOnLinux) for many games it won’t be so easy. Vermintide 2 uses EAC but as it turns out it might not be the right kind . Their reply to a thread requesting Proton support on the games' Steam Forum explained that there are actually two versions of EAC, one that uses Epic’s Online Services (EOS) and one that doesn’t. This fix may be true for those that do use Epic’s Online Services, but it turns out that may only be for a few newer and first party Epic Titles. Vermintide 2 is one of the many games using the non-EOS version of Epic’s Anti-Cheat.
They estimate there’d be a lot of work in converting a non-EOS version to an EOS and thus receive Proton support and run on Steam Deck, but they are looking into whether or not it’s a viable move.
Other development teams like Tripwire Interactive have also pointed out the potential compatibility issue with Epic’s Anti-Cheat, but it’s not even the only service to potentially cause problems. DayZ devs have also come out saying it’s unlikely they’ll be bringing their game to Steam Deck and many believe this is because of its BattleEye anti-cheat software.
Given how many games these problems could affect, this could be a real barrier for the Steam Deck. That being said, it’s still a nifty piece of hardware that many are looking forward to. Of course, demand will need to come from customers to let developers know it’s worth their time, so if enough people pick up the platform it will be supported. That being said, if you don’t want to bother with this side of things perhaps the premium AyaNeo Next handheld PC is going to be more your speed.
Valve says the Steam Deck is still on track for a February launch, so hopefully we’ll find out more then.