# Implementation Progress — Skirmish (C64)

## Status: BUILDABLE MVP BASELINE

Last updated: 2026-05-28

---

## What Exists Now

### Project structure

```
skirmish-game/
├── src/
│   ├── skirmish.asm       # Entry point, raster sync, shared state
│   ├── input.asm          # Keyboard + joystick polling
│   ├── game-logic.asm     # Turn flow, movement, combat, occupancy
│   ├── enemy-ai.asm       # Closest-target AI and movement
│   ├── render.asm         # Sprites, HUD, board markers
│   ├── data.asm           # Tables, text, sprite bitmaps
│   ├── skirmish.inc       # Shared constants
│   └── c64.cfg            # ld65 memory layout
├── docs/
│   ├── GDD.md
│   ├── TECHNICAL-PLAN.md
│   └── C64-CHEATSHEET.md
├── build.bat
├── run-vice.bat
├── debug-vice.bat
├── Makefile
├── README.md
└── skirmish.prg
```

### Core gameplay implemented

- 8x8 tactical board with coordinate markers
- 3 player units and 3 enemy units
- Single-step turn flow:
  - player selects a unit
  - player moves or attacks
  - enemy team takes its turn
  - win/lose is checked
- Adjacent melee combat for both teams
- Unit HP tracking and death removal
- Greedy enemy AI using Manhattan distance
- Selected-unit highlight via sprite color
- Restart flow after win or loss

### Controls implemented

- `Q` or joystick fire: cycle selected player unit
- `W`, `A`, `S`, `D` or joystick directions: move or attack
- `E` or space: end turn
- `R`: restart after game over

### Engine and rendering implemented

- BASIC stub starts game with `RUN` -> `SYS 2061`
- Raster-driven frame sync installed through IRQ vector
- Main loop updates once per IRQ tick
- 6 hardware sprites used for units
- HUD shows current phase, turn count, selected unit, and all unit HP
- Sprite bitmaps and lookup tables are linked into C64-visible RAM
- Occupancy grid rebuilt from unit state to avoid stale collision state

---

## Build Verification

### Confirmed

- `build.bat` assembles and links successfully with local `ca65` and `ld65`
- Output artifact currently builds as `skirmish.prg`

### Current artifact

- `skirmish.prg` size: 2617 bytes
- Most recent successful local build: 2026-05-28

### Not yet verified

- Full gameplay smoke test inside VICE
- Sprite alignment and board readability in the live emulator
- Joystick port 2 behavior in VICE input mapping
- End-to-end win/lose flow by playtesting

---

## Known Gaps

### High priority

1. Run the build in `x64sc` and verify the boot path, controls, and turn flow.
2. Confirm the raster-driven loop behaves correctly on a real VICE session.
3. Tune board readability if the current dot-grid is too sparse under sprites.

### Medium priority

1. Add attack and death feedback such as flash or simple SID beeps.
2. Add a stronger title/opening screen.
3. Add a clearer wait indicator and maybe a per-unit action prompt.

### Low priority

1. Add obstacles and richer pathing.
2. Add ranged attacks or special abilities.
3. Add difficulty scaling or multiple waves.

---

## Notes

- The previous tracker text described files that did not actually exist yet.
- The source tree and build scripts now exist and match this document.
- The PRG boot path was corrected so the BASIC stub jumps to the real contiguous load address.
- The next milestone should be emulator validation and gameplay polish, not project scaffolding.