src

Source code

This folder contains the new Typescript implementation of Eastern Front 1941. Source files are in *.ts and Jest unit tests are in *.test.ts. README.md is this file. CHANGES.md captures a history of many of the cartridge-specific features that were implemented after I had the base APX code mostly working. It might have useful context as to how and why I made particular design choices. TODO.md tracks a running list of future tasks which might or might not get implemented. Various static configuration choices are parameterized in config.ts. Also see the implementation notes with more background on the design.

The app is split into three components, described in more detail below:

• engine/ - the headless game engine
• antic/ - a generic Atari-like character-based display window
• app/ - the UX for the game itself

Game engine

The core game engine is a headless EventEmitter rooted in game.ts. The "public" API across all engine modules is exposed in index.ts for bundling purposes.

Much of the cartridge storage budget is taken up by the various maps and tables needed to play the game, just like a physical wargame. These tables are directly extracted from the original binaries via scripts/ and expressed in a more accessible form here.

• defs.ts - Core data type definitions, enums and so forth
• scenarios.ts - Definitions for each of the difficult levels and scenarios
• map-data.ts - ascii representations of the game map derived from the binary data
• oob-data.ts - Orders of battle (lists of unit data) used in the various scenarios, extracted from binary data

The game and AI logic are defined in:

• game.ts - the core game engine, managing the map (map.ts) and order of battle (oob.ts)
• map.ts - manages the game board which contains units and cities
• grid.ts - a generic system to manage the cartesian grid upon which the map sits
• oob.ts - manages the order of battle, little more than a specialized array of units
• unit.ts - manage an individual unit and its interactions with other units like combat
• think.ts - implements the original APX AI system
• codec.ts - a suite of integer coding and decoding utilities used primarily to encode and decode compact game state
• rng.ts - replaces Atari's truly random byte generator with a simple reproducible random number generator. This makes the game a pure function of an initial seed value, making it easier to test and reason about.

User interface

The display is based on a simple model/view/controller implementation in app/, which leverages a generic Atari-like 'video terminal' window provided by antic/.

antic/:

• palettes.ts - Various options for converting from Antic to RGB color
• anticmodel.ts - models a variable size character display, with vt52-like formatting codes
• anticview.ts - maps a display region to HTML

app/:

• app.ts - the main external entry point, simply instantiates an app controller
• appctrl.ts - the app controller which manages game state between setup, order and turn resolution
• appkeys.ts - key handlers for the app controller, mapping key presses to controller actions by game state
• appmodel.ts - the app display model, which maps the game state into a set of antic windows
• appview.ts - the app view, a declarative mapping of the model to HTML with MithrilJS
• help.ts - implements the help popover with some display scrambling for fun