The filename NXBUNSC-Fix-Repair-Steam-Generic.rar strongly suggests this is a "warez" or software piracy tool—specifically, a crack, patch, or fix designed to bypass DRM (like Steam licensing) for a specific game or software.
C:\Program Files (x86)\Steam\steamapps\common\YourGame\).steam_api.dll or steam_api64.dll and rename them to steam_api.dll.backup rather than deleting.Steam and Community Support
Multiplayer Restoration: For players using unofficial versions of a game, this fix often redirects the game’s network calls through a "Spacewar" (AppID 480) workaround, allowing friends to play together via Steam. NXBUNSC-Fix-Repair-Steam-Generic.rar