Glider PRO — a paper aeroplane, a house, and a lot of updrafts Free & open source
1994 · John Calhoun / Casady & Greene · System 7 · Basilisk II (Mac IIfx) · 640×480 at 8-bit colour
Guide updated September 2026 · needs your own copy
You are a paper aeroplane. You are indoors. Gravity is pulling you down and the only thing keeping you up is the hot air coming out of the heating vents, so the whole game is a slow negotiation with a house that is full of candles, drips, rubber bands and a cat.
Glider PRO is the 1994 peak of a series John Calhoun had been refining since 1988, and in 2016 he put the whole thing — code and art — on GitHub under the GPL. It is free in every sense.
Controls
| Left / Right arrows | Steer the glider |
| Down arrow | Toggle the battery or helium when you have one |
| Space | Pause |
| Cmd-N | New game |
| Esc | Back to the menu |
John Calhoun published the full Glider PRO source code on GitHub in 2016 under the GNU General Public License version 2, together with the game's assets. It is one of the very few commercial Macintosh games of the era to be freed outright by its author.
Source and modern ports
- softdorothy/GliderPRO — John Calhoun's original source, GPL-2.
- Aerofoil — the maintained multiplatform port, with the level editor and the community houses.
How it works & what to expect
| Machine | Macintosh IIfx, 16 MB RAM, 640×480 at 256 colours |
|---|---|
| System | System 7.5.3 |
| Emulator | Basilisk II, compiled to WebAssembly |
| Speed | Comfortable. Glider was written to run on modest hardware. |
If you want Glider PRO at a modern resolution with gamepad support and the level editor, there is a maintained port called Aerofoil built on Calhoun's released source. It is the better way to play seriously. What is here is the original, as it shipped.
The house, and everything in it
Each room is a single screen and the glider drifts through it left to right, or right to left, or up through a hole in the ceiling. The furniture is the level design:
- Heating vents and air ducts. Your engine. Hover over one to climb; the entire skill of the game is learning to ride them.
- Candles. Fly through the flame and the paper burns. Obviously.
- Drips and steam. Wet paper does not fly.
- Rubber bands and paper clips. Fired at you by things that resent your presence.
- The cat. A problem.
- Batteries, helium, and the paper aeroplane power-ups. Temporary thrust, temporary lift, and extra lives.
Glider PRO shipped with several houses and a built-in editor, and the community built hundreds more. That editor is the reason the game is still alive: there is far more Glider content made by players than by Casady & Greene.
Why it was freed
John Calhoun wrote the first Glider in 1988 as shareware, and the series ran through Glider 3.1.4 and Glider 4.0 before Casady & Greene published Glider PRO commercially in 1994. Casady & Greene closed in 2003.
In 2016 Calhoun put the complete source on GitHub under the GPL — the Macintosh Programmer's Workshop project files, the resource forks, the artwork, everything. That is rarer than it sounds. Most Macintosh games of that era are stuck in limbo because the publisher dissolved and nobody is sure who inherited what. Glider PRO is simply free, because the person who wrote it decided it should be.
Questions people ask
Is Glider PRO free?
Yes, genuinely. John Calhoun released the source code and the game assets on GitHub in 2016 under the GNU GPL version 2.
What is the goal?
Get the paper aeroplane through the house to the end without burning, soaking or shredding it. Later houses add doors you have to find keys for and rooms that only open once you have done something elsewhere.
How do I stay in the air?
Ride the updrafts. The vents and ducts blow upward — position yourself over one and you rise. Most deaths are from trying to cross a room with no lift in it.
Can I build my own houses?
Glider PRO shipped with a level editor and it is in this version. The modern Aerofoil port has a better one and can import the hundreds of houses the community made.
Should I play this or Aerofoil?
Aerofoil if you want to play a lot of it — modern resolution, gamepad support, the community houses. This one if you want the 1994 game exactly as it was, in one click, with nothing installed.
Is there an earlier version?
Several. Glider 4.0 from 1991 is the direct predecessor and Calhoun released its source too. It is simpler, black and white, and charming in its own right.