What is a passthrough mod?
Two real games running at once, stitched together so one plays inside the other. Here's how it works, without the jargon.
In autumn 2026 a new kind of mod took over: Minecraft inside Skyrim, Spider-Man swinging through Batman's Gotham, Minecraft blocks on Outer Wilds planets. They look impossible, because nobody rebuilt Minecraft inside Skyrim. They didn't have to.
The short version
A passthrough mod runs two real games at the same time and makes them talk to each other.
- The host is the game you see and play in. In SkyCraft that's Skyrim.
- The guest is the game being brought in. In SkyCraft that's Minecraft, and it runs hidden in the background.
A small mod inside each game sends information back and forth dozens of times a second. The host then draws the guest's stuff (blocks, mobs, a character's moves) inside its own world. To you, it feels like one game.
What actually gets passed through?
Taking SkyCraft as the example, here's what happens every frame:
- Where you are. Minecraft owns your player, so it decides how you move and jump. Skyrim gets your position and camera and draws you in its world.
- What the ground looks like. Skyrim's terrain, rocks and buildings are copied into the hidden Minecraft as invisible collision, so Minecraft's physics "feel" Skyrim's world. Getting this right is most of the work, and it's why early versions sometimes drop you through the floor.
- What's on screen. Minecraft's blocks, items and HUD are sent over and drawn by Skyrim, with Skyrim's own lighting and fog.
- What just happened. You hit a Skyrim bandit with a Minecraft sword, so the damage is translated into Skyrim's numbers. An explosion in one game becomes an explosion in the other.
- Who's around. NPCs from one game can get invisible stand-ins (called proxies) in the other, so each game's systems can "see" them.
Other projects use other tricks. ArkWeb puts Spider-Man (hidden) on the same spot as Batman and copies his pose. The universal-modder GTA V example layers Minecraft's finished picture, with depth, into GTA's frame, so blocks correctly hide behind GTA's buildings.
Why now?
Two things came together:
- SkyCraft published a clear, open-source design (MIT licence) that others could copy. Most passthrough mods since are ports of it: OWCraft, ValCraft, HaloCraft, FalloutCraft, PeakCraft and more. Check the Forks & ports section on its page.
- AI coding agents made the tedious parts (hooking a game, writing the bridge on both sides, endless testing) fast enough for one person to finish in days. Several projects say openly that they were built that way, and some, like ArkWeb, even use an agent to set the mod up on your PC.
What it isn't
- Not an emulator or a port. You need both games installed, and both really run.
- Not a remake. Nobody rebuilt Minecraft. That's what makes these fast to build, but it's also why they need decent hardware (see Will my PC run it?).
- Not the same as a Rust rewrite or a recomp. Those are different, related trends. See Rewrites, recomps and mashups.
The catch
These are young, experimental fan projects. Expect rough edges.
- They're often locked to exact game versions. A Skyrim or Spider-Man update can break them until the author catches up.
- Most connect exactly two games.
- Many need you to build them yourself from source. The Playable filter shows the ones with a ready download.
- They need your own copies of both games, and they only work in single-player. Never use them in online games with anti-cheat.
Ready to try one? Start with Your first passthrough mod.