Fallout et Tu: Fallout 1 rebuilt inside the Fallout 2 engine

A reimplementation, not a reskin of the original game

Fallout et Tu takes Fallout 1 and runs it inside Fallout 2's engine. The project states the aim in plain terms: it replicates Fallout 1 in 2 almost one to one. That word almost matters, because a great deal of what the project ships is Fallout 2 machinery grafted onto a Fallout 1 map.

The primary language is Pascal, and the top-level tree shows how the work is arranged. The Fallout2 directory holds the engine and the mod itself, including a nested Fallout2/Fallout1in2 directory that carries the project-specific documentation. Resources holds assets, including the game's logo image, and Tools holds whatever support tooling comes with the project. NEWS.md sits at the root as a changelog.

So this is not a patch that tweaks the original executable. It is a conversion in the strict sense: the original game's world, items and scripting are re-expressed for a different engine. That is the source of both its strengths and its limits, since everything Fallout 2 does well is available, and everything that depends on Fallout 1's engine idioms has to be reworked.

A feature list that is mostly optional

The project publishes a long feature list, and then tells you something important about it: most of these features are optional and can be toggled on and off via a dedicated configuration file.

That single design decision is what makes the conversion usable in more than one way. You can run it as a faithful Fallout 1 with the additions switched off, or as a hybrid with party members in combat, merchant restocking and new encounter maps switched on. A configuration file rather than a compiled constant is the difference between those modes.

The additions listed are specific. The Hero Appearance mod is integrated, with four named looks, Bald Dude, Long Hair Dude, Black Dude and Punk Girl. Merchants restock inventory in the Fallout 2 style. Doors open and close automatically. Selected Fallout 2 weapons have been added to the game world sparingly, in ways the project says do not break the balance, and weapons can be upgraded in the Fallout 2 style. Encounter maps include classic Fallout 2 style caverns and new mining site maps, and Fallout 2 critters such as Geckos are there to be stumbled over. The original endgame being too easy is answered with a tougher mutants setting, and the game can be continued after the main story is completed. The list also claims a body of bugfixes that makes the game more stable than even the original with patches.

Party members that fight, level up and wear their armour

Three of the party features describe the sharpest departure from Fallout 1. Party members can be controlled in combat. Party members level up and change their appearance based on worn armour. And party members and generic NPCs can be pushed out of the way.

In the original game the party is a set of scripted followers with fixed behaviours and a fixed look. Here, control passes to the player during encounters, so a companion becomes a combatant with a build rather than a scripted action on the world map. The armour rule follows from the same engine difference: because the engine can drive an NPC's appearance from what it wears, the visual identity of a companion changes as you equip it.

The third item is smaller but telling. Being able to push party members and generic NPCs aside is a Fallout 2 grid navigation behaviour, and it signals that the world is now laid out on the Fallout 2 grid rules rather than Fallout 1's.

For a player, the consequence is that armour stops being only a stat decision, since buying a piece for a companion changes how that companion looks. For someone writing a mod on top, it is the more interesting half: the party is now addressable in combat, which the original engine did not offer.

Encounter maps, Geckos and a harder endgame

Exploration changes shape too. The project adds classic Fallout 2 style cavern and new mining site encounter maps, and the Fallout 2 critters that come with them, Geckos being the named example.

Fallout 1 moved between a world map and discrete encounter areas, but with a much smaller and more regular set of them. Fallout 2's encounter map system is one of the engine's better known features, and inheriting it means a different rhythm of play: more frequent transitions, more varied terrain, and combat encounters that are no longer limited to the locations the original game shipped with.

The tougher mutants setting exists for players who finish the game too easily, and the ability to continue playing after the main story is completed turns the conversion into something you can keep returning to rather than a single playthrough.

The balance of all this is worth keeping in view. The project describes the added Fallout 2 weapons as added sparingly and in ways that do not break the game balance, which is a claim about intent rather than a measurement. Nobody has published a balance analysis of this conversion, so if the challenge curve matters to you, expect to tune the configuration switches yourself rather than trusting a fixed difficulty level.

Why run a Fallout 1 mod on the Fallout 2 engine at all

The project gives the reason for the whole approach, and it is a modding argument rather than a graphics one. It states that because of the more accessible modding features of Fallout 2, the project allows the creation of complex modifications, which would not be possible with the engine of the first game.

That is the real difference from an ordinary Fallout 1 total conversion. A Fallout 1 mod stays on the original engine and inherits its limits: the original scripting capability, the original asset formats, the original interface conventions. This conversion inherits the Fallout 2 side of all of that, plus the Fallout 2 content in the form of added weapons, weapon upgrade rules, merchant restocking behaviour and encounter maps.

For a player, the practical difference between the two routes is the feature list above. For a mod author, the difference is where the ceiling is: the same codebase that gives you party members in combat and appearance driven by armour is the base on which the project claims complex modifications become possible.

The conversion also inherits the cost of that engine. Fallout 2 behaviour shows up in the ways the feature list cannot hide, from automatic doors to pushed-aside NPCs, and it means the conversion is bound to the Fallout 2 installation it runs on rather than being self-contained.

Downloading the zip and finding the real instructions

The download is a single archive linked from the project page as the latest version:

https://github.com/rotators/Fo1in2/releases/latest/download/Fallout1in2.zip

Installation is not described in the top-level README. Instead the project points you at a document inside the Fallout 2 tree, with an anchor named mod-installation:

Fallout2/Fallout1in2/README.md#mod-installation

A second anchor, additional-content, is where the project keeps its list of the modifications it has made, which is the place to look if you want to know exactly what a given build changed rather than what the feature list promises in general.

The project homepage is a thread on the No Mutants Allowed forum, nma-fallout.com, which is where the community side of this conversion lives. Between the release archive, the in-tree installation document and the forum thread, the documentation is spread across three places, and the top-level README is only the signpost.

One practical note for anyone building the whole thing rather than installing a release: the project lists its language as Pascal and ships a Tools directory, so the toolchain for compiling it is part of the repository rather than something you are told to install separately. The release archives are the path of least resistance.

Frequent builds, and a licence that is not settled

The release history shows sustained activity. Recent versions include v2.0.3911 on 2026-10-14, v1.16.3771 on 2026-06-03 and v1.15.3735 on 2026-02-19, and the last push to the repository was on 2026-10-17. The trailing numbers look like build identifiers rather than semantic versions, which tells you the project ships frequently, and the jump to a 2.0 line in October 2026 marks a milestone release rather than a routine bump.

Upgrading is cheap in that scheme. Each version arrives as a replacement zip, and the optional features are controlled by a configuration file rather than by a save file format, so a new build does not carry a long migration chain. What you do need is a compatible Fallout 2 installation, which is the real coupling in this project.

The licence is the weak point. The project's licence field is listed as unknown, and the top-level entries of the repository contain no licence file among the .gitattributes, .github, .gitignore, Fallout2, NEWS.md, README.md, Resources and Tools directories. For personal use that hardly matters, but if you plan to redistribute the archive, bundle it with your own project, or publish modifications built on it, the terms are not established by anything in the repository and you need to ask the authors directly. That is a documentation gap rather than a legal opinion about who owns the work.

Editorial conclusion

Fallout et Tu suits players who finished Fallout 1 and want the same world rebuilt on a newer engine, and modders who want a base where complex modifications are possible, which the project says the original Fallout 1 engine would not allow. It is the wrong choice if you want a clean or faithful Fallout 1 experience, since party behaviour, encounter pacing and the endgame all change, and it is the wrong choice if you need clear reuse terms, because the licence is listed as unknown and there is no licence file at the top level. Verify three things before you commit: that the optional feature switches in the configuration file can be turned down to a near original experience, that the installation instructions under Fallout2/Fallout1in2 match the way you install Fallout 2 mods, and that the build you download corresponds to the engine version you actually have installed.

Frequently asked questions

Official sources

1. Issues
2. Project website
3. README
4. Releases
5. rotators/Fo1in2 on GitHub