README

Dark Planet — DOS Game (1998) · Windows Port

Originally released in 1998. Reverse-engineered and ported to Delphi VCL in 2026.

What is this

Dark Planet is a DOS side-scrolling action game originally written in Turbo Pascal using BGI256 graphics. This repository contains a full Windows port — not a wrapper, not an emulator, but a clean rewrite in Delphi VCL that runs natively on modern Windows.

Original game: Alexander Friz (@alexfrize · LinkedIn) All graphics and sprites: Ilia Kusmin (@rm3g25 · LinkedIn) Windows port: Ilia Kusmin

Why this is engineering, not just a port

The original code used DOS-specific techniques that have no direct equivalent in Windows:

1. Banker's rounding killed the enemies Turbo Pascal Round(2.5) = 3. Delphi Round(2.5) = 2. One digit difference — enemies walked straight through walls into the sky. Fix: replaced Round() with Trunc(x + 0.5) to match original half-up behavior.

2. Off-by-one shifted every sprite Delphi open array parameters are always 0-indexed, regardless of the caller's array bounds. The entire sprite list was shifted by -1: earth tiles appeared in the sky, enemies showed wrong animation frames. Fix: N := 0 instead of N := 1 in the file parser. One character. Hours of debugging.

3. XOR rendering made corpses disappear DOS trick: draw a sprite twice with XOR = erase it. No memory needed, no cleanup. Windows double buffering clears the canvas every frame — corpses vanished instantly. Fix: full double-buffer architecture: FBack (static tiles) + FBuf (composited frame) → StretchBlt.

What was rewritten

The core game logic — collision formulas, enemy AI boundaries, animation state machine — is preserved exactly from the original.

What was improved

• Parabolic jump physics — replaced linear pixel-per-tick with velocity + gravity (FVelY += 0.55 per tick)
• Shoot while jumping — with correct frozen-Y hit detection at the moment of firing
• Alt+Enter fullscreen — scales to any resolution while preserving 320×200 aspect ratio with letterboxing
• Title screen — CDRAGON.PIC with fade-in text, matches original intro feel

Controls

How to run

1. Download the latest release zip from Releases
2. Extract anywhere
3. Run DPport.exe

No installation, no dependencies. Single folder, runs on any Windows.

How to build from source

Requirements: Delphi 12 or newer (Community Edition works)

1. Clone the repository
2. Open src/DPport.dpr
3. Build (Ctrl+F9) — exe compiles to the project root next to the game assets
4. Run

Repository structure

dark-planet/
  src/
    DPport.dpr
    DPport.dproj
    GameMain.pas
    GameMain.dfm
  SPRITES.NEW/
    *.IMG          -- all game sprites (graphics by Ilia Kusmin)
  LEVEL1.SF!       -- level 1 scenario
  LEVEL1.ITM       -- tile list
  LEVEL1.STF       -- enemy sprite list
  LEVEL2.SF!       -- level 2 scenario
  CDRAGON.PIC      -- title screen image
  README.md
  .gitignore

About the original

Dark Planet was developed in 1998 using Turbo Pascal 7 with BGI256 graphics library. The game ran in DOS VGA Mode 13h (320×200, 256 colors). All sprites were drawn pixel-by-pixel using a custom DOS sprite editor — keyboard-only, no mouse.

Port developed by Ilia Kusmin · iliakuzmin.dev