Install co-op.
Then press F8.
Get Vamp MiSide Co-op running in your own game, then invite a friend into a private session. Here’s the setup, one step at a time.
A work in progress. Shared story and Mita systems are implemented. A complete campaign with two real players is still unverified. Every player needs their own legitimate MiSide copy.
Before you begin
Use the same mod version as your friends. This build targets MiSide 0.93L for Windows; another game build may be refused by the compatibility check.
- Have MiSide installed through Steam.
- Keep a backup of your single-player saves.
- Close MiSide and any running Vamp co-op server before installing.
No separate .NET installation is needed for the compiled package. Multiplayer progress uses its own save files.
Extract the whole package
Download the v0.3.0 ZIP, then right-click VampMiSideCoop-v0.3.0.zip and choose Extract All. Open the extracted VampMiSideCoop folder.
Open a terminal inside this folder: click its address bar in File Explorer, type powershell, and press Enter. Run the commands below there.
Where is your game installed?
Steam → MiSide → Manage → Browse local files. Copy that folder’s address here if it differs from the default. Commands below update to match.
Enter a full Windows folder path without line breaks.
Add BepInEx
BepInEx lets MiSide load the mod. If the compatible BepInEx 6 IL2CPP loader is already installed, keep it and skip this command.
powershell -NoProfile -ExecutionPolicy Bypass -File .\scripts\InstallLoader.ps1 -DownloadAndInstall -GameDir 'C:\Program Files (x86)\Steam\steamapps\common\MiSide'The script downloads official build 791 and checks its expected file hash. Do not substitute BepInEx 5 or a Mono loader.
Let the game prepare once
Launch MiSide normally through Steam. The first BepInEx launch prepares local game files and can take longer than usual.
Wait until the main menu appears, then close the game completely. Keep your PowerShell window open.
Install, then verify
Run these two commands in order. Wait for each to finish before running the next.
powershell -NoProfile -ExecutionPolicy Bypass -File .\scripts\Install.ps1 -GameDir 'C:\Program Files (x86)\Steam\steamapps\common\MiSide'powershell -NoProfile -ExecutionPolicy Bypass -File .\scripts\Verify.ps1 -GameDir 'C:\Program Files (x86)\Steam\steamapps\common\MiSide'You should see an installation success message and a report that the installed file hashes were verified. Verification checks the files; it does not certify every co-op story sequence.
Launch MiSide. Press F8.
Start MiSide through Steam again. Press F8 to open Vamp MiSide Co-op. Choose Host to create a private session, or Join to enter a friend’s details.
Play together, even from another country.
Country does not restrict joining. The host’s server must be reachable, and everyone needs the same mod version and a compatible game installation.
If you’re hosting
- Open F8 → Host.
- For other PCs, enable Allow LAN / VPN connections.
- Start the session and share the host address, port, certificate fingerprint and player password privately.
If you’re joining
- Open F8 → Join.
- Enter the address and connection details supplied by your host.
- Leave the optional host key empty unless you own the dedicated server.
Friends in different countries
Use a private VPN that connects both PCs, or a public IP with the selected TCP port forwarded to the hosting PC and allowed through its firewall. A private VPN can avoid needing an inbound public route when it is configured for both players.
127.0.0.1 only reaches your own PC. A home LAN address usually works only on that same network. Carrier-grade NAT can prevent direct public joining.
The host PC must stay on and awake. This Cloudflare website serves the guide; multiplayer traffic goes to the session server. International connections and full two-player campaign completion remain unverified.
Share the player password and fingerprint privately. Never send status.json or the host key to ordinary guests.
Something not working?
No matching fixes. Clear the search to see all topics.
F8 does nothing or the co-op menu is missing
Confirm that the compatible BepInEx 6 IL2CPP loader is installed. Complete its first launch, close the game, then run Install and Verify again from the extracted package. Launch through Steam. On some keyboards use Fn + F8.
The installer says MiSide is still running
Exit MiSide fully and stop any co-op server running from its installed mod folder. Then retry. The installer deliberately refuses to change files used by a running game.
Access denied or a folder cannot be written
Check the game folder above. If Windows prevents writing to your Steam library, run PowerShell with the rights required for that folder, or use a Steam library you own. Reopen it in the extracted mod folder before running the command.
My friend cannot join from another country
Enable LAN / VPN connections for the host. Check the address, VPN routing or public port forwarding, and the host’s firewall. Guests must not use 127.0.0.1. If direct public hosting is behind carrier-grade NAT, forwarding on your router alone is not enough. Keep the PC awake.
The certificate or password is rejected
Ask the host to confirm the current fingerprint and player password privately. Recreating a server certificate changes its fingerprint. Do not disable certificate verification. The host key is a separate secret, not the guest password.
The game version or native build is unsupported
This package was built for MiSide 0.93L. The mod refuses unknown native game hashes. Use a compatible mod build for your legitimate installed game; don’t replace game binaries to force it to load.
Need to remove the mod?
Close MiSide and the installed server first. In the extracted package folder, run:
powershell -NoProfile -ExecutionPolicy Bypass -File .\scripts\Uninstall.ps1 -GameDir 'C:\Program Files (x86)\Steam\steamapps\common\MiSide'The default uninstall preserves settings, saves and the loader. Read docs/Installation.md in the package before removing the owned loader too.