rugen vs MUGEN vs Ikemen GO

Three engines play M.U.G.E.N content today. M.U.G.E.N is the original by Elecbyte. Ikemen GO is an open-source successor written in Go. rugen is an open-source engine written in Rust, built around compatibility and online play. All three load the same character and stage files, so you do not have to choose once and for all: your chars/ folder works in each.

At a glance

	M.U.G.E.N 1.1	Ikemen GO	rugen
Source code	Closed	Open (MIT)	Open (MIT / Apache-2.0)
Last release	1.1 beta 1, August 2013	Active	Active
Windows	Yes	Yes	Yes (x64, x86, ARM64)
Linux	Older builds only	Yes	Yes (.deb, .rpm, tarball)
macOS	Older builds only	Yes	Yes (Apple Silicon and Intel)
Steam Deck	Through Proton	Yes	Yes, with a Deck layout
Online play	No	Built-in netplay	Rollback netcode, ranked, rooms, spectators
Play online with a fighter your opponent lacks	No	No	Yes, packages are sent by the server
Online tournaments	No	No	On rugen.dev, brackets called by the server
Loads .def .cns .cmd .air .sff .snd	Yes	Yes	Yes, unchanged
Scripting beyond CNS	No	Lua	No, CNS only
Menu languages	English	English	11 languages
Updates	Manual	Manual	In-game updater

Why pick rugen

• Your old content, unchanged. A character made in 2005 loads as it is. On first launch rugen packs it into one .rgc file and plays that. See the compatibility status.
• Online that holds up. Rollback netcode was designed in from the start, with a sync test that proves the simulation is deterministic. See netcode.
• No “you need the same characters” problem. The server checks each fighter, sends packages to the opponent and spectators, and deletes them after three days. See bring your own character.
• Fairness checks. Every fighter gets a verdict (fair, unbalanced or blocked) so ranked matches stay sane. See fairness.
• Runs on modest machines. 0.7.0 cut memory per fighter by more than half and added a low-spec render mode. See performance.

Moving from MUGEN to rugen

1. Install rugen for your system.
2. Copy your MUGEN chars/ folders or zips into rugen’s chars/, and your stages into stages/. Keep each character in its own folder or archive.
3. Start rugen. It converts everything once in the background; fighters appear on the select screen as they finish.
4. Run rugen list to see every fighter id, or rugen verify <id> to check one before playing online.

Your MUGEN select.def is not needed: rugen builds the roster from the folder. Screenpacks go into themes/, see screenpacks and themes.

Moving from Ikemen GO

Characters and stages written for plain MUGEN move over the same way. Content that relies on Ikemen GO extensions (Lua, Ikemen-only state controllers or triggers) loads only as far as its MUGEN parts go; rugen check <id> lists what it does not understand.

Questions

Is rugen a MUGEN emulator? No. It is a new engine that reads the same files and follows the same rules, written from the public MUGEN documentation and tested against real community characters.

Is it free? Yes. No ads, no paid tiers, and the code is on GitHub.

Can I play MUGEN online with friends? Yes. Share a room code or use quick match. See online play.