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Hello CCM!
I've released v1.1.0 of bgIW5, my Modern Warfare 3 LAN/offline client.
The big news: bgIW5 now supports the current Steam version of Modern Warfare 3 (2.0 build 15, the 64-bit version Steam has delivered since August 2026), next to the old 1.4 build. Multiplayer (private matches and matchmaking), Special Ops co-op (private and matchmaking) and the campaign work with it over LAN.
As before: one PC runs Hostmode and the others connect to it. No external master server and no internet connection are needed.
Download and setup guide:
What's new in v1.1.0
Features
Requirements
Installation
The launcher backs up the original file (steam_api64.dll for the Steam version, steam_api.dll for 1.4). You can restore it using Remove bgIW5.
Start the launcher normally. Installing into a protected folder such as Program Files may ask for administrator permission for that step.
How to play
What's next?
Some of the things on my list:
These are planned improvements and investigations, with no fixed release dates. Some depend on what turns out to be possible.
Have a suggestion or a setup you'd like to help test? Let me know!
Thanks to everyone who has kept playing and sharing feedback over the years!
If you find a bug, please reply with what happened, your game build, and whether you were hosting or joining. Include any error message / relevant logs and crashdumps. Logs and crash reports are in %LOCALAPPDATA%\bgIW5.
I've released v1.1.0 of bgIW5, my Modern Warfare 3 LAN/offline client.
The big news: bgIW5 now supports the current Steam version of Modern Warfare 3 (2.0 build 15, the 64-bit version Steam has delivered since August 2026), next to the old 1.4 build. Multiplayer (private matches and matchmaking), Special Ops co-op (private and matchmaking) and the campaign work with it over LAN.
As before: one PC runs Hostmode and the others connect to it. No external master server and no internet connection are needed.
Download and setup guide:
What's new in v1.1.0
- Support for the current Steam version of Modern Warfare 3 (2.0 build 15, 64-bit). The launcher sees which version you have and installs the matching files.
- Multiplayer with the Steam version: private matches, party invites, joining through the friends list, and matchmaking.
- Special Ops co-op with the Steam version, in private lobbies and through matchmaking.
- The launcher starts the Steam version directly with your settings.
- The message after login now points to bgamer.dev.
- Logs stay small: a log over 5 MB starts over at the next game start.
Features
- A completely redesigned launcher, the same as bgT5's.
- Private matches with invites. Players can also join the host through the in-game friends list.
- Matchmaking (Find Game) over LAN, starting from 2 players.
- The in-game friends list shows every player on the host, on every PC.
- Matchmaking lobbies show player names instead of "Matched Player".
- Special Ops co-op over LAN.
- Set up a dedicated server directly in the launcher: game mode, maps, player limit and password. The server starts its map rotation automatically and appears in the in-game server browser.
- Your stats, classes and playercard are saved locally and synced with the host.
- Find hosts on your network without entering an IP address.
- Choose the network you play on, including LAN, Wi-Fi or VPN.
- The launcher finds Modern Warfare 3 and can install, update or remove bgIW5.
- No administrator rights needed for playing or hosting.
- Logs and crash reports to help with bug reports.
Requirements
- A legitimate installation of Call of Duty: Modern Warfare 3. Game files are not included.
- Supported versions:
- the current Steam version: 2.0 build 15 (64-bit iw5mp.exe and iw5sp.exe). The Steam client has to be running.
- the old 1.4 build (build 382) of iw5mp.exe, iw5sp.exe and iw5mp_server.exe.
Everyone in a LAN plays the same version. Other builds start without bgIW5's patches. - Windows with .NET Framework 4.8, which is included in Windows 10 version 1903 and later, and Windows 11.
Installation
- Download v1.0.0 from the website above.
- Extract the ZIP to a folder of your choice.
- Open bgIW5Launcher.exe. If it doesn't find Modern Warfare 3 automatically, select your game folder.
- Click Install when prompted.
The launcher backs up the original file (steam_api64.dll for the Steam version, steam_api.dll for 1.4). You can restore it using Remove bgIW5.
Start the launcher normally. Installing into a protected folder such as Program Files may ask for administrator permission for that step.
How to play
1. Enter your nickname.
2. Switch on Hostmode and allow network access if Windows asks.
3. Under Your IP, select the network you play on.
4. Click This PC so the Host field points to your own address.
5. Start Multiplayer, open a private match and invite the others from the friends list. For Special Ops, start Campaign & Spec Ops and open a private Special Ops lobby.
Keep the launcher running while hosting.
2. Switch on Hostmode and allow network access if Windows asks.
3. Under Your IP, select the network you play on.
4. Click This PC so the Host field points to your own address.
5. Start Multiplayer, open a private match and invite the others from the friends list. For Special Ops, start Campaign & Spec Ops and open a private Special Ops lobby.
Keep the launcher running while hosting.
1. Click Find and select the host, or enter the host's IP address manually.
2. Wait for "LAN service answers".
3. Start Multiplayer, or Campaign & Spec Ops for Special Ops.
4. Accept the host's invite, or join the host through the in-game friends list.
Find may not work across routers or some VPNs. In that case, enter the host's IP manually.
2. Wait for "LAN service answers".
3. Start Multiplayer, or Campaign & Spec Ops for Special Ops.
4. Accept the host's invite, or join the host through the in-game friends list.
Find may not work across routers or some VPNs. In that case, enter the host's IP manually.
Everyone playing through the same host is matched together. Find Game starts a match from 2 players.
Click Server next to Multiplayer, choose your settings and click Start server.
The dedicated server needs the 1.4 iw5mp_server.exe. Steam's "MW3 Dedicated Server" download is only a placeholder now ("temporarily disabled"); the launcher tells you if your folder only has that.
Enable Also run Hostmode on this PC if this PC will provide the LAN service too.
The server starts its map rotation automatically. Players join it from the server browser in Multiplayer.
You can also use your own main\server.cfg. It needs start_map_rotate at the end; the launcher warns you if it's missing.
The dedicated server needs the 1.4 iw5mp_server.exe. Steam's "MW3 Dedicated Server" download is only a placeholder now ("temporarily disabled"); the launcher tells you if your folder only has that.
Enable Also run Hostmode on this PC if this PC will provide the LAN service too.
The server starts its map rotation automatically. Players join it from the server browser in Multiplayer.
You can also use your own main\server.cfg. It needs start_map_rotate at the end; the launcher warns you if it's missing.
If Windows asks, allow bgIW5Launcher.exe, iw5mp.exe, iw5sp.exe and iw5mp_server.exe.
For a firewall rule made by hand:
• On the host: TCP 3078, 3079 and 3080 (3080 is new: the Steam version's login), UDP 3078, 3079 and 27950
• Game traffic between players: UDP 3074 (or the next free port)
• Dedicated server: UDP 27016 by default, plus 27015 and 27017
For a firewall rule made by hand:
• On the host: TCP 3078, 3079 and 3080 (3080 is new: the Steam version's login), UDP 3078, 3079 and 27950
• Game traffic between players: UDP 3074 (or the next free port)
• Dedicated server: UDP 27016 by default, plus 27015 and 27017
Extract v1.1.0 over your old bgIW5 folder (or into a new one) and start the launcher. It offers Update for a game folder with an older bgIW5. Your players and stats stay where they are (%LOCALAPPDATA%\bgIW5).
When it installs into a folder of an older, unnumbered bgIW5 version, the launcher keeps that version's steam_api.dll, and Remove bgIW5 puts it back.
Use Import to bring an existing player over from an old bgIW5 game folder. If someone else hosted your games, import from that host's game folder to bring your progress over.
When it installs into a folder of an older, unnumbered bgIW5 version, the launcher keeps that version's steam_api.dll, and Remove bgIW5 puts it back.
Use Import to bring an existing player over from an old bgIW5 game folder. If someone else hosted your games, import from that host's game folder to bring your progress over.
• Steam version (2.0 build 15) and 1.4 players can't play together. Everyone in a LAN needs the same version.
• The Steam version needs the Steam client running.
• Dedicated servers run with the 1.4 iw5mp_server.exe only. Players on the Steam version can't be expected to join them.
• Dedicated server: Gun Game and One in the Chamber can't be selected, and time and score limits use the game's defaults.
• The campaign and moving stats to another host aren't tested yet.
• IPv4 only.
• Windows 7 is untested and requires .NET Framework 4.8 separately.
• The Steam version needs the Steam client running.
• Dedicated servers run with the 1.4 iw5mp_server.exe only. Players on the Steam version can't be expected to join them.
• Dedicated server: Gun Game and One in the Chamber can't be selected, and time and score limits use the game's defaults.
• The campaign and moving stats to another host aren't tested yet.
• IPv4 only.
• Windows 7 is untested and requires .NET Framework 4.8 separately.
What's next?
Some of the things on my list:
- More dedicated server options: Time and score limits, Hardcore and more match rules in the launcher.
- Bots on dedicated servers.
- Better guides: More setup examples for LAN, VPN play and dedicated servers.
These are planned improvements and investigations, with no fixed release dates. Some depend on what turns out to be possible.
Have a suggestion or a setup you'd like to help test? Let me know!
Thanks to everyone who has kept playing and sharing feedback over the years!
If you find a bug, please reply with what happened, your game build, and whether you were hosting or joining. Include any error message / relevant logs and crashdumps. Logs and crash reports are in %LOCALAPPDATA%\bgIW5.
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