Undertale: Undertale Together Mod for Windows

Bring cooperative play to Undertale

Undertale Together is a free fan-made mod that adds two-player functionality to Undertale. Instead of experiencing the game's characters and story on your own, you and a friend can explore, fight, and solve puzzles together. The mod preserves the core narrative and mechanics of Undertale while introducing cooperative control and interaction.

Local and online modes

The mod supports both local and networked play.

• Local play: two players can share the same computer. Each person can use one half of the keyboard, or one player can use a gamepad while the other uses keys.
• Online sessions: you can connect remotely, but this typically involves extra setup. You may need connection helpers (VPN/relay tools), to forward ports, or to adjust antivirus and firewall settings for the connection to work reliably.
• Compatibility note: offline setup is straightforward, while online matches may require installing third-party utilities and changing security settings on your system.

What changes (and what stays the same)

Undertale Together adds cooperative control and interaction without rewriting the story.

• New dynamic: having two people present alters fight flow, puzzle solving, and the social feel of the game world.
• Story and core gameplay: the original writing, characters, and major systems remain intact so the familiar Undertale experience is preserved.
• Replay value: shared play can reveal fresh approaches to encounters and conversations, making a familiar game feel new.

Who should try it

This mod is suited to both longtime fans and newcomers.

• Veterans: if you’ve already played Undertale, cooperative play is a way to revisit the game with different strategies and shared decision-making.
• New players: those encountering Undertale for the first time can experience it alongside a friend, making the narrative moments more interactive and social.
• Casual players: cooperative sessions can make tricky sequences easier and more fun with another person helping.

Quick setup checklist

• Confirm you have the mod files and an Undertale installation that matches the mod’s required version.
• For offline play, connect a second controller (optional) or agree on keyboard halves for each player.
• If you want to play online, prepare to install any recommended networking tools and to configure your firewall or router as needed.
• Back up your game files before installing mods, so you can restore the original if necessary.

If you want, I can provide links to common setup tools, step-by-step installation instructions, or troubleshooting tips for online play. Which would you prefer?