Gungeon Online

Online co-op for Enter the Gungeon over Steam (play with friends anywhere, no port forwarding) or LAN (same home network).

Very early alpha — side project. Built as a hobby in spare time. Expect bugs, desyncs and crashes; both players need the exact same version; back up your saves first. No support or guarantees.

It can do this so far (all experimental):

• Host a friends-only Steam lobby and invite a friend through the Steam overlay, or accept a friend's invite
• Host or join a LAN game by IP address, or find LAN games automatically
• Pick the name other players see
• See your partner in game: character, animations, gun, pet, ghost glow and status effects
• Host-led runs on the same seed; bullets, thrown items, blanks and floor effects are shared
• Shared enemy health and deaths; enemies can target either player
• Co-op deaths: become a ghost, get revived from a chest
• Tables, breakables and rolling barrels; shared pause; optional PvP

Not synced yet: enemy attacks themselves (each game simulates them), items dropped on death, and much more.

Requirements

• Enter the Gungeon (Steam play needs the Steam version of the game)
• BepInExPack for EtG (your mod manager installs it automatically)
• Both players need the same version of this mod

How to use

Press F8 in game to show or hide the Gungeon Online window.

Your name: type it in the Name box and click Save. Leave it empty to use your Steam name.

Steam:

1. Host: click Host on Steam, then Invite friend and pick a friend in the Steam overlay.
2. Friend: accept the invite in Steam.

LAN:

1. Host: click Host on LAN. The window shows your LAN address (like 192.168.1.20:27460).
2. Friend: click Find LAN games and pick the host, or type the address and click Join.
3. The first time you host, Windows may ask whether to let Enter the Gungeon through the firewall. Allow it on private networks.

The status changes to Connected and shows your ping.

Settings

In BepInEx/config/gungeononline.multiplayer.cfg (or your mod manager's config editor):

• PlayerName: the name others see (empty = Steam name)
• ToggleWindowKey: the key that shows/hides the window (default F8)
• Port (LAN section): the UDP port for LAN games (default 27460; host and friends must match)

Compatibility

Gungeon Online doesn't change any game code yet, so it should work alongside other mods.

Troubleshooting

• Check BepInEx/LogOutput.log in your mod profile. Gungeon Online's lines start with [Gungeon Online].
• LAN game not found? Make sure both PCs are on the same network and the firewall allows the game, then try typing the address instead.

Credits

• Built on BepInEx and the game's own Steamworks.NET
• Built with help from Claude (Anthropic), an AI assistant

License

MIT

Support

If you enjoy this side project, you can support me on Ko-fi: https://ko-fi.com/alexjustalex