Flappy Bird 95

A Flappy Bird clone written in Borland Delphi 1.0 for Windows 3.11. 16-bit Object Pascal, one form, one TTimer, no external libraries.

Requirements

• Windows 3.1 / 3.11 (tested in QEMU/UTM with MS-DOS 6.22 + WfW 3.11)
• Borland Delphi 1.0 (the "AppBuilder" 16-bit IDE)
• 8 MB RAM is enough; the game runs fine on an emulated 486

Build

1. Copy src\ to a project directory, e.g. C:\FB95\, and copy res\ into it so you end up with C:\FB95\RES\BG.BMP and friends.
2. Open PROJECT1.PRJ in Delphi, then Run > Build All, then Run > Run.

A prebuilt 16-bit executable is in bin\PROJECT1.EXE; put a copy of res\ next to it to run it without building (needs Windows 3.1x or a 16-bit capable Windows / emulator).

Where the bitmaps are looked up

FindResDir in UNIT1.PAS resolves the resource folder at start-up, relative to the running executable (GetModuleFileName), in this order:

1. <exe folder>\RES\ — the normal layout
2. <exe folder>\..\RES\ — handy when the EXE ends up in a subfolder
3. C:\RES\ — legacy fallback

If none of them contains BIRD.BMP the program says so in a message box and quits instead of raising a file-not-found exception.

Controls

SPACE — flap, start, and restart after a crash.

How it works

The whole game is one unit, UNIT1.PAS:

• Resources next to the EXE — see Where the bitmaps are looked up.
• Fixed 25 fps — Timer1.Interval = 40, and Timer1Timer calls Update(Sender, Timer1.Interval) followed by Draw(Sender).
• Double buffering — everything is drawn into an off-screen TBitmap created once in Setup, then blitted to the form canvas in one Draw call.
• Transparency without an alpha channel — every sprite has a 1-bit mask BMP. BlitMasked AND-blits the mask (cmSrcAnd) and then OR-blits the picture (cmSrcPaint), which is how sprites were composited in 1995. Masks are converted to screen-compatible bitmaps once at start-up so the per-frame blits do not depend on the device context colours.
• Pipes — the one-pixel-high pipe body (PIPEB.BMP) is stretched into a full-height column once, the pipe mouth (PIPEE.BMP) is pasted on top, and the upside-down variant is built by copying the mouth row by row. Drawing a pipe is then just two masked blits of a slice of that prerendered column.
• Bird — BIRD.BMP is a 102x24 sprite sheet, three 34x24 frames, advanced every 120 ms.
• Physics — Velocity := Velocity + Gravity * Delta / 1000 and Y := Y + Round(Velocity); a flap sets Velocity := VelocityDeltaUp.

Tuning constants live at the top of the unit: HoleHeight, GroundSpeed, Gravity, VelocityDeltaUp, PipeGap, PipeMargin.

Notes on this Delphi build

This is a pre-release Delphi 1 ("AppBuilder"): there is no ExtCtrls and no SysUtils unit, so TTimer and TImage come from StdCtrls and integer to string conversion is done with a small NumToStr wrapper around Str.

Known issue

In 256-colour video modes the ground strip comes out greener than the source bitmap, because the 8-bit DIB palettes are never realised into the screen palette. Selecting and realising the palette before the blits would fix it.

Layout

src/   UNIT1.PAS  UNIT1.FRM  PROJECT1.PRJ  PROJECT1.OPT  PROJECT1.RES
res/   BG.BMP  BIRD.BMP  BIRD-M.BMP  GROUND.BMP
       PIPEB.BMP  PIPEB-M.BMP  PIPEE.BMP  PIPEE-M.BMP
bin/   PROJECT1.EXE       prebuilt 16-bit binary
tools/ fb95-source.img    720 KB FAT12 floppy image with UNIT1.PAS
docs/  screenshots

Made with Claude

The project started as a skeleton with the pipes, the sprite animation and the transparency still marked {TODO}. It was finished with Claude, which read the unit straight out of the QEMU disk image, wrote the missing code, and then had to get it back into a 1995 IDE: the virtual machine forwards no letter keystrokes and no mouse, so every revision went in on a hand-built 720 KB FAT12 floppy image (tools/) and Delphi 1 was driven entirely by Alt-menu keyboard navigation.

Artwork

The bitmaps in res/ are Flappy Bird style sprites. They are included so the project builds as-is; they are not original work of this repository and are not covered by its licence.