One more time, please
Have you tried running a game from 1997 lately? We have. Sometimes it works. More often it asks for a DirectX version nobody ships any more, a 16-bit installer Windows refuses to start, or a CD drive your laptop never had. Then it crashes on a CPU that is "too fast". Emulation helps, and we have nothing against it — but it is one more layer between you and the game, and it only solves today's problem. What happens when the platform under the emulator goes away too?
ENCORE — Engines of Nostalgia, Clean Open REimplementations — is a different answer. We rebuild the games themselves, from scratch, one to one.
Why now?
Reimplementing a game used to be a labour of love that took a small team years. Some of the best ones — think of OpenTTD, OpenRCT2 or OpenMW — took many years, and a few are still going. Is it different now? Yes, and the numbers make the case better than we can. Sheep took about 29 hours of agent time. Grand Theft Auto, two days. Oni, 3,655 functions of Bungie's engine, plays through all its levels after six. Those figures are the span of each project's commit history — the agents' time, not counting the human hours spent directing, reviewing and play-testing. And they are not toy demos: they are function-by-function ports of the original programs, verified with deterministic hashes, and in three of them checked against the original's own machine code.
What changed is engineering experience combined with coding agents and good tooling — Ghidra, emulators for differential testing, deterministic hashes, and a runtime that takes the platform out of the problem. We take that opportunity to make the games we love available to the next generations, on whatever platform exists, or will exist, in the future.
Why rebuild and not emulate?
Because a reimplementation is plain, portable source code. It compiles for platforms that did not exist when the game came out, and it will compile for the ones that do not exist yet. It can read the original data straight from a disc image, without an installer. It can fix nothing — on purpose — or it can add a widescreen mode, when that makes sense, without touching how the game plays.
Faithful comes first. Every port keeps the original's quirks and bugs, because they are part of the game. Modern additions — 16:9 and 16:10, higher resolutions, gamepads — are opt-in, and each project proves with hashes that switching them off gives you exactly the original.
Why gasm?
Every ENCORE game targets gasm, a small WebAssembly game runtime. The game is compiled once to a .wasm module, and thin runners give it video, audio, input and files. The same module runs on Linux, macOS, Windows and in the browser, with no changes and bit-identical game state on all of them.
Is it a lock-in? Not really. Each port keeps all of its platform code in one backend file, so a fully native build — SDL, a console SDK, whatever comes next — is a backend away. That matters where WebAssembly performance is not enough.
What "clean" means
"Clean" in ENCORE means that nothing of the original ships: no code, no art, no sound, no data. Every port reads all of that from your own copy at run time. It does not mean a legal clean-room process. Most of the ports are written function by function from a disassembly of the original program, by people (and agents) who studied that program closely, and we say so on every project page.
What we don't do
We don't ship games. We don't own the rights to them, and we never include their code, art, sound, music or data. You bring your own copy — the disc you kept, a second-hand one, or a copy bought from a store such as GOG, whose mission is to preserve games as well. More on that in Bring your own copy.
Good neighbours
Many of these games have communities that kept them alive long before we arrived: wikis, format documentation, modding tools, earlier reimplementations. We build from the original programs, never by forking someone else's decompilation, and we credit every community resource we lean on. Before starting a game we look for existing projects; if one is active, we would rather help it than race it. See On AI for how we work.
Join in
Everything is open: the code of every port under the GPL, the technical guides, and a set of agent skills that carry what we learned to the next project. If there is a game you want to see back, the guides are where to start. If you do start one, let us know — there is room for more of us.