More than a decade after its release, Undertale is still finding new ways to surprise players. While the game was originally designed as a single-player experience, fans have now figured out a clever method to play it with friends online. The trick doesn’t involve an official update from developer Toby Fox, though. Instead, it relies on the free Steam game Crashphalt and Steam Remote Play.

The discovery recently caught the attention of Crashphalt’s developer, who noticed something strange while checking the game’s Steam page. Although Crashphalt launched in 2018 and had very little activity for years, it suddenly started receiving hundreds of new reviews and a massive increase in players. Even more confusing was that most of the reviews barely mentioned Crashphalt at all. Instead, they were talking about Undertale.

How to play the Undertale Together mod

After looking into it, the developer discovered that players were using Crashphalt as part of a workaround to play Undertale Together, a fan-made multiplayer mod. The mod itself only supports local co-op, but players found a way to use Steam Remote Play to bring online multiplayer into the game. Players are simply using Crashphalt as a proxy for co-op Undertale.

The process works by copying Crashphalt’s files into a modded Undertale installation and renaming Undertale’s executable so Steam recognizes it as Crashphalt. Because Crashphalt supports Steam Remote Play, Steam allows players to invite friends online, effectively letting them experience Undertale together even though the game was never built for online multiplayer.

This unusual workaround had a huge effect on Crashphalt’s popularity. According to SteamDB data, the game’s peak player count jumped from just a handful of players to over 100 around the time the tutorial explaining the method was published. The increase happened almost overnight and has continued to bring new players to the game’s Steam page ever since.

Interestingly, the developer still isn’t sure why Crashphalt was chosen. There are plenty of free games on Steam that support Remote Play, but for some reason, the community settled on Crashphalt. Rather than being upset that people weren’t actually playing their game, the developer has taken the situation surprisingly well.

They said they’re happy Crashphalt has found a second life, even if it’s in an unexpected way. Undertale was one of the games that inspired them to become a developer, so seeing their own project help fans enjoy Undertale with friends is something they find genuinely exciting.

About the Author

Abdul Haddi

Abdul is a tech writer and Editor for PC Guide, specializing in all things tech, gaming, and hardware.