Before you start

01 Confirm the game runs unmodded

Launch Deadly Dozen Reloaded from Steam, get into a mission, and quit. This sounds like a wasted two minutes and it is not: if the game has a problem of its own — a broken shader cache, a missing Visual C++ runtime, a corrupted download — you want to know that now, while there is nothing else in the folder to blame.

If it does not run clean, fix that first. In Steam: right-click the game → Properties → Installed Files → Verify integrity of game files.

02 Find the game folder

Everything in this manual happens in one folder: the one containing DeadlyDozenReloaded.exe. In Steam, right-click the game → Manage → Browse local files. Explorer opens exactly where you need to be.

The path depends on which Steam library the game landed in:

Default library
C:\Program Files (x86)\Steam\steamapps\common\Deadly Dozen Reloaded

Second drive library (this manual's screenshots)
F:\SteamLibrary\steamapps\common\Deadly Dozen Reloaded

Keep that window open. From here on, <game folder> means this directory and nothing else.

03 Confirm the architecture

Deadly Dozen Reloaded is a 64-bit Unity IL2CPP game. Its compiled code lives in GameAssembly.dll, a 29.8 MB PE32+ image with seven sections and a preferred base of 0x180000000. There is no 32-bit build of this game, so there is no situation in which a 32-bit BepInEx is the right answer.

You can confirm it in two seconds without any tools. In the game folder, check that GameAssembly.dll exists and is roughly 30 MB. That file is IL2CPP's signature — a Mono-backend Unity game would have a Managed folder inside its _Data directory instead, and would need BepInEx 5.

04 Get the archives and a real extraction tool

All three packages are .rar archives, and all three ship with this manual — they are in the downloads/ folder beside these pages, and every install section links to the one it needs. Each one also carries a mirror on StixsworldHD's own paid Google Drive account, which is frequently the faster of the two. Front matter has all three in one place if you would rather grab them now.

Windows Explorer cannot open RAR files on its own. Use one of:

• 7-Zip — free, opens RAR, and the one to reach for if you do not already have something.
• WinRAR — the reference implementation, and what these archives were built with.
• NanaZip — a maintained 7-Zip fork from the Microsoft Store, if you prefer that route.

05 Clear space and warn your antivirus

Budget 1 GB free on the drive the game is installed on. The packages themselves are about 210 MB unpacked, and the first launch generates a few hundred megabytes more of interop assemblies and cache.

Antivirus

A DLL named winhttp.dll appearing next to a game executable is, structurally, exactly what DLL-hijacking malware looks like. Windows Defender and most third-party scanners will occasionally quarantine it. This is a false positive — BepInEx is open source and widely used — but you have to deal with it or the loader will vanish mid-install with no explanation.

Add an exclusion for the whole game folder before extracting. In Windows Security: Virus & threat protection → Manage settings → Add or remove exclusions → Add an exclusion → Folder.

Steam settings that get in the way

• Steam Overlay — leave it on. It coexists with BepInEx here. Only disable it if you later see a crash on startup and want to eliminate a variable.
• Launch options — leave them empty. Nothing in this manual needs one.
• Cloud saves — unaffected. Nothing here touches save data.

06 Understand what you are not backing up

You do not need to back up the game. Nothing in this manual modifies, patches, replaces or deletes a single shipped file. Every file added is a new file, and the whole install can be reversed by deleting what you added — section 09 covers that.

Steam's Verify integrity of game files is your reset button. It restores anything shipped that has gone wrong, and it leaves BepInEx alone because BepInEx's files are not part of Steam's manifest. That means verifying does not uninstall your mods, which is useful to know in both directions.