A free game on Steam saw a 1700% player increase because people use its files to play multiplayer Undertale

Published Jul 28, 2026, 2:06 AM EDT Simon is a Computer Science BSc graduate who has been writing about technology since 2014, and using Windows machines since 3.1. After working for an indie game studio and acting as the family's go-to technician for all computer issues, he found his passion for writing and decided to use his skill set to write about all things tech. Since beginning his writing career, he has written for many different publications such as WorldStart, Listverse, and MakeTechEasier. However, after finding his home at MakeUseOf in February 2019, he would eventually move on to its sister site, XDA, to bring the latest and greatest in Windows, Linux, and DIY electronics. Sign in to your XDA account Summary Crashphalt saw a 1683% player spike after being used to enable Undertale multiplayer via Remote Play People patched Crashphalt's Remote Play into Undertale, renaming executables and swapping files to trick Steam The developer is fine with it and is glad Crashphalt lets friends play Undertale together It's not too uncommon for a little-known game on Steam to be shot into popularity due to someone discovering it, but none are quite so weird as the story of Crashphalt. The game has seen a 1683% player count boost in recent months, but only because people are downloading it so they can play a totally different game online with their friends. A multiplayer Undertale mod skyrockets Crashphalt's player count All publicity is good publicity, I suppose As spotted by PC Gamer, the developer of the game Crashphalt, Retro_Specter, posted on Reddit to discuss what happened with their game. A few months ago, they noticed that the free game they published in 2018 had suddenly gained 1638% more players in December 2022, taking the average player count from single digits to just over 100. For four years, Retro_Specter's game had been doing better than ever, and they had no idea. Strangely enough, all of the recent comments mentioned Undertale, so Retro_Specter got to digging. Turns out, in December 2022, someone posted a video showing how to play Undertale multiplayer online. There was a mod to handle more players, but Undertale itself was not coded to support multiplayer gaming over IP, nor did it allow for Remote Play. So, people searched for a free game that did support Remote Play, and they happened to come across Crashphalt. As the developer puts it: I dunno why they chose Crashphalt. The only requirement for the hack is that the has Remote Play enabled, and I guess it does help that Crashphalt is free. But I imagine there are tons of games that fit that bill. Crashphalt was just the lucky game chosen for the honor. So yes, people were downloading Crashphalt, stripping it of its Remote Play code, stuffing it into Undertale's files, and renaming Undertale's executable to Crashphalt to trick Steam into allowing Remote Play with the title. Now people can use Remote Play to play Undertale together. The developer did highlight a review for Crashphalt that read, "I wonder how the developer feels knowing that literally no one cares about their game and only uses it to mod other games." Turns out, the developer is fine with it; given how Crashphalt has some years on it now, they've moved on to other projects. They're just pleased people are using their game to get multiplayer Undertale working.