Run the shortcut. The game will create a fresh save file. Do not load your modern Patch 17/18 saves —they will crash Patch 15.
The ULTRAKILL Speedrunning Discord maintains a verified archive of old patches for tournament use. Look for the #legacy-builds channel. Never download from random file-hosting sites (Mediafire, Mega, RandomBoat.net) —malware disguised as game patches is rampant.
The keyword "" typically refers to compressed files containing the Full Arsenal Update , a major milestone in ULTRAKILL 's development history originally released on April 15, 2024 . While modern versions have surpassed this—most recently reaching Patch 17d4 with the release of Layer 8: Fraud in 2026—Patch 15 remains a legendary point of entry for many players. The Core of Patch 15: The Full Arsenal Update ULTRAKILL.Patch.15.rar
Patch 15 saves to a different registry path than modern versions. Navigate to HKEY_CURRENT_USER\Software\Arsi\ULTRAKILL in Regedit. Export the key for backup. To restore saves, you will need to merge the registry file manually.
: Improved performance and added Cyber Grind fog options. Run the shortcut
Released on April 15, 2024, this patch is widely considered one of the most transformative updates to the game's combat system. It finalized the core weapon sets, allowing players to have a complete arsenal for the first time. Steam Community New Weapon Variations
For competitive players, Patch 15 represents the "golden mean" between the exploitable loosness of Patch 14 and the strict balance of Patch 16. The keyword "" typically refers to compressed files
Installing ULTRAKILL.Patch.15.rar is a relatively straightforward process. Here's a step-by-step guide:
: Fixed bugs in Layer 8 (Fraud) and optimized the Cyber Grind.
Patch 15 finalized the first half of Layer 7: "Greed," introducing the treacherous Violence layer’s opening level, 7-1: "Garden of Forking Paths" . This level introduced mirror-based teleportation puzzles mixed with wave-based enemy spawns.