Setting up MUGEN — the free fighting-game engine behind SaltyBet — comes down to three things: install an engine, drop character folders into one directory, and list them in one config file. You can have a working roster swinging punches in about 15 minutes, and you don’t need to know a single line of code to do it.
This is the complete, current guide: which engine to pick in 2026, where to get characters without nuking your PC, and the exact select.def edit that puts a fighter on your roster. By the end you’ll have the same engine SaltyBet runs 24/7 — just pointed at whatever roster you feel like building.
You need two things: an engine and characters. The engine is the program that runs the fights; characters are the fighters you download and add to it. Stages (backgrounds) and screenpacks (the menu skin) are optional polish you can add later.
The first real decision is which engine to run, because there are two, and they’re both free:
For a brand-new user in 2026, we’d point you at IKEMEN GO. It’s the one that’s still being updated, it runs on a Mac or a Linux box (MUGEN 1.1 does not), and it plays practically all the same content. Reach for classic MUGEN 1.1 only if you’re chasing an old screenpack or a character that specifically wants it. If you want the backstory on how these two engines came to exist, we wrote the whole 27-year saga in The History of MUGEN.
IKEMEN GO: Grab a ready-to-use build from the releases page on GitHub.[2] Stable releases use tags like v1.0.0; if you want the newest features, there are nightly builds too. Download the ZIP that matches your operating system and extract it wherever you like — your Desktop is fine.
To run it:
Ikemen_GO.exe.I.K.E.M.E.N-Go.app. The download is unsigned, so macOS quarantines it on first launch — the bundled Ikemen_GO.command clears the quarantine flag and starts the app for you.Ikemen_GO_Linux — run ./Ikemen_GO_Linux from the extracted folder. There’s also an Ikemen_GO.desktop file if you’d rather have a normal menu entry.One gotcha on macOS and Linux: Ikemen_GO.command ships without the executable bit set, so double-clicking it does nothing useful. Run chmod +x Ikemen_GO.command once in a terminal and it’ll work from then on. (On Linux, Ikemen_GO_Linux is the only top-level file that arrives already executable, which is why we point you there first.)
If audio doesn’t work on an older build, install OpenAL from its official site — some versions rely on it for sound.
MUGEN 1.1 Beta: Elecbyte’s original site has been offline for years,[1] so the 1.1 build now lives on community archive sites. Download the archive, extract it, and run mugen.exe. It’s Windows-only and needs no installer — MUGEN has always been a “just unzip and run” program.
Either way, launch it once before adding anything. Both engines ship with a couple of default fighters (IKEMEN GO’s mascot Kung Fu Man among them) so you can confirm it opens and a fight actually starts.
Characters are fan-made and distributed as ZIP files on community warehouses. The big, community-monitored ones in 2026 are:
One safety rule, and it’s non-negotiable: scan everything you download. These are user-uploaded files, and no warehouse can guarantee every upload is clean.[3] Run new downloads through your antivirus, or drop the ZIP on virustotal.com (owned by Google) for a free multi-engine scan before you extract. Stick to reputable sites with ratings and comments, and you’ll almost never have a problem — but scan anyway.
This is the part people think is complicated. It isn’t. There are two moves: drop the folder in, then list it in select.def.
1. Extract the character. Unzip what you downloaded. Inside you’ll find a folder containing files that end in .def, .sff, .snd, .air, and .cns — that’s the character. The .sff holds the sprites, the .snd holds the sounds, and the .def is the master file that ties it together.
2. Move that folder into chars/. Every engine has a chars/ directory. Drop the whole character folder in there. Do not bury it inside an extra subfolder — the character folder should sit directly inside chars/.
3. Add one line to select.def. Open data/select.def in any text editor (Notepad is fine). Under the [Characters] section, add a line with the character’s folder name. The simplest form is just the name:
KungFuManOr, to pair the fighter with a specific stage and set where they fall in Arcade mode, use the fuller format:[4][5]
Ryu, stages/ryu.def, includestage=1, order=1Here the stages/ryu.def field is what ties a stage to the fighter; includestage=1 just also adds that stage to the stage-select screen (set it to 0 to keep the stage tied to the fighter but hidden from selection). And order=1 sets which Arcade-mode opponent group they belong to — it does not choose their square on the select screen. Where a fighter lands on the grid follows the order you list them in [Characters] (a blank line leaves an empty slot), so to move someone, move their line.
Save the file, launch the engine, and your fighter is on the select screen. That’s the entire process — a folder and a line of text.
The single most common gotcha: by default the engine looks for a .def that matches the folder name.[5] If you dropped in a folder called Ryu but the master file inside is ryu_mvc.def, a bare Ryu line won’t find it. You have two fixes: rename the .def so it matches the folder, or — cleaner, especially when a folder ships several .def variants — point at it explicitly with the folder-and-file path, Ryu/ryu_mvc.def. The explicit path also lets you choose which build loads without renaming anything in the download.
Stages work the same way, one directory over. Put the stage’s .def file (and any art it references) into the stages/ folder, then either pair it with a character by naming it in that character’s stage field (as above — includestage=1 also adds it to the stage-select list) or list it under the [ExtraStages] section of select.def in the form stages/yourstage.def.[4] Now your fighters have somewhere to fight that isn’t the default training room.
No — but it’s the upgrade that makes your build feel like a real game. A screenpack is the menu skin: the character-select grid, the fonts, the versus screen, and the lifebars — it brings a bit of zest and lets you customize the main mechanics of your instance. It’s controlled by data/system.def. Swapping in a custom screenpack changes the whole look and how many character slots your roster has — the stock select screens are small, so if you’re planning a 200-fighter roster, a big-grid screenpack is what makes room for them. Download screenpacks from the same warehouses as characters, follow the included readme (each one points system.def at its own assets), and treat it as a Step 5, not a Step 1.
| Symptom | Likely cause | Fix |
|---|---|---|
| Character doesn’t appear on select screen | Not listed in select.def, or the screen is full | Add the line; use a larger-grid screenpack |
| “Cannot load” / crash on select | Folder name ≠ .def name | Rename to match, or use the explicit Ryu/ryu_mvc.def path[5] |
| Character folder has a folder inside it | Extra nesting from the ZIP | Move the inner folder directly into chars/ |
| No sound from a fighter | Missing or misnamed .snd | Re-download; confirm the .snd sits beside the .def |
| Works in one engine, not the other | Version mismatch (a 1.1-era build in an older engine) | Use IKEMEN GO or MUGEN 1.1 for the widest compatibility[2] |
| MUGEN 1.1 Beta | IKEMEN GO | |
|---|---|---|
| Maintained? | No — last release 2013[1] | Yes — active open-source dev[2] |
| Platforms | Windows only | Windows, macOS, Linux[2] |
| Online play | No | Yes — rollback netcode[2] |
| License | Non-commercial | MIT (commercial use allowed)[2] |
| Content compatibility | The reference standard | Targets 1.1-Beta parity[2] |
| Best for | Old screenpacks, maximum legacy compatibility | New users, Mac/Linux, online matches |
Both play the enormous back-catalog of community characters. If you’re just starting out and want the engine with a future, IKEMEN GO is the pick. If you’re recreating a specific classic full-game or screenpack that expects MUGEN 1.1, use that.
Here’s the fun part: once you’ve done this, you understand SaltyBet from the inside. SaltyBet is nothing more than MUGEN running in Watch mode — AI versus AI — streamed to Twitch 24/7, with viewers betting Salty Bucks on the outcome.[6] The 10,000-plus fighters in SaltyBet’s roster are exactly the kind of community-made characters you just learned to install, dropped into chars/ and listed in a select.def, same as yours. The wild balance, the boss-tier monsters, the joke characters that somehow go 90% — that’s all MUGEN, running exactly as the community built it.
The difference is scale: SaltyTrack has recorded over 638,000 of those matches, which is what lets us tell you a fighter’s real win rate before you bet on it. If you’re curious why some of these community characters dominate, we broke it down in Why Do Some MUGEN Characters Always Win? and ranked the outright monsters in The 25 Strongest MUGEN Characters.
How do I install a MUGEN character?
Extract the character’s ZIP, move its folder into the engine’s chars/ directory, then open data/select.def and add the folder name under the [Characters] section. By default the folder name and the character’s main .def file must match; if they differ, either rename the .def or point at it explicitly with a folder/file path like Ryu/ryu_mvc.def.
Is MUGEN free?
Yes. Both MUGEN 1.1 Beta and the open-source IKEMEN GO engine are free to download and use, and the community-made characters and stages are free as well. MUGEN’s original license is non-commercial; IKEMEN GO uses the MIT license, which allows commercial use.
Should I use MUGEN 1.1 or IKEMEN GO?
For a new user in 2026, IKEMEN GO is the better default: it’s actively developed, runs on Windows, macOS, and Linux, and adds online play while staying compatible with MUGEN 1.1-era content. Use classic MUGEN 1.1 Beta only if a specific screenpack or full-game build requires it.
Is it safe to download MUGEN characters?
The engines themselves are safe, but characters are user-uploaded files, so scan every download with antivirus software or virustotal.com before extracting it. Stick to established, community-monitored warehouses like The MUGEN ARCHIVE, AK1, and Mugen Free For All.
Why isn’t my character showing up in the game?
The two usual causes are that you forgot to add its line to select.def, or the character-select screen is full. Add the entry under [Characters], and if your roster is bigger than the default grid, install a screenpack with more slots.
Is SaltyBet just MUGEN?
Yes — SaltyBet runs the MUGEN engine in Watch mode (AI vs AI) and streams the fights to Twitch around the clock. Its 10,000-plus fighters are the same kind of community-made characters you install yourself.
Built a roster and want to see how those fighters really perform? The SaltyTrack Chrome Extension shows AI-powered predictions, win rates, and head-to-head records across SaltyBet’s 10,000+ MUGEN fighters — the same engine you just set up, analyzed across 638,000+ matches. Free, no account, no nonsense.
SaltyBet uses virtual currency only. No real money is wagered or exchanged. SaltyTrack is not affiliated with SaltyBet, Elecbyte, or the IKEMEN GO project.