ZZT, in Elixir, over a WebSocket

A port of Tim Sweeney's 1991 shareware classic ZZT, reading .ZZT world files directly and rendering the 80×25 CP437 display inside a Phoenix LiveView. Stats tick on the server, diffs go out over a WebSocket, and your browser paints the bear that wants to eat you.

Why does this exist

It shouldn't. "Just because you could" etc.

ZZT ran on a single-digit-MHz 8088 with a CGA card that wrote directly to B800:0000, and it ran fine. The game loop was a tight while over Board.Stats[] polling the keyboard at the speed of a malfunctioning DMA controller. Porting that loop to a stack where every on-screen character is serialized as a map diff, gzipped, punted through a WebSocket, then stitched into the DOM by a virtual-DOM-ish patcher... is not a sensible architectural choice. The 5¼" floppy this shipped on had more spare I/O budget than we do.

But: the reference port is Pascal, Elixir pattern matches sum types like destructible-vs-pushable-vs-walkable tiles with basically zero ceremony, %{{x, y} => {element, color}} is a perfectly respectable way to model a board, and LiveView's existing diff machinery happens to be pretty good at "push 1,500 tiny colored squares around at 10 Hz." So it works. It shouldn't, but it does. Carefully unwrapping what the reference is doing one element at a time has been more fun than it has any right to be.

Running it

mix setup
mix phx.server

Then open localhost:4000 and pick a world. Drop any .ZZT file into priv/games/ and it shows up in the library.

Controls

Key	What it does
Arrows	Move / push / pick up
Shift + arrow	Shoot
T	Light a torch
P	Pause
Esc	Dismiss a scroll, or bail back to the library
A (on title)	About

What's in

Roughly ZZT's full gameplay surface — enough to play through TOWN.ZZT end to end:

• Every stock element: lions, tigers, bears, centipedes, ruffians, sharks, slime, pushers, conveyors, bullets, stars, spinning guns, bombs, blink walls, transporters, energizers, passages, doors/keys, scrolls, breakable/normal/fake/invisible walls.
• The ZZT-OOP interpreter — #walk, #go, #try, #shoot, #send target:label, #if flag, #give/#take, #become, #put, #change, #bind, #zap/#restore, #lock/#unlock, #die, #endgame, conditions, text scrolls, :TOUCH / :SHOT / :BOMBED / :ENERGIZE / :THUD labels.
• Dark rooms + torches (with the ellipse radius).
• The full sidebar including the torch gauge, pausing indicator, and board timer; the title-screen Monitor menu with Play / World / About.
• ReenterWhenZapped boards, the "Ouch!" / "Game over" message system, board timers that damage you, bomb fuse + blast, ricochets, and all the little touches.

What's out

• Sound. ZZT queued PC-speaker tunes on essentially every interaction; the port is silent. Web Audio is the next frontier.
• Save/restore, high scores, the board editor. None of the non-game menu commands are wired up — R, Q, H, E on the title screen render but no-op.
• Super ZZT.

Built on the shoulders of

• Tim Sweeney for the original.
• Adrian Siekierka's reconstruction-of-zzt — the annotated Pascal source release. Nearly every Elixir module here has a GAME.PAS:1234 / ELEMENTS.PAS:567 breadcrumb pointing at its reference implementation.
• The Museum of ZZT for preserving worlds.