v0.1.0 — Cosmo runs natively

Cosmo's Cosmic Adventure: Forbidden Planet (Apogee, 1992), running natively.
No DOSBox, no emulator, no virtual machine.

Every archive below is self-contained and includes the shareware Episode 1, so
it plays as soon as you unzip it. If you own Episodes 2 and 3, drop their
COSMO2.* and COSMO3.* files in the same directory and the launcher will
offer them.

Download	For
cosmo-v0.1.0-macos-universal.zip	macOS 11+, Apple Silicon and Intel
cosmo-v0.1.0-linux-x86_64.zip	Linux, x86-64
cosmo-v0.1.0-windows-x86_64.zip	Windows, x86-64

macOS will refuse to open the binaries the first time, since they are unsigned:
right-click → Open, or xattr -dr com.apple.quarantine . in the folder.

Arrow keys move, space jumps, alt bombs, F1 helps, Q then Y
quits and saves. Everything is rebindable from the game's own menu.

What this is

The port is built from the game's own code rather than a reimplementation. It
uses Cosmore, Scott Smitelli's
reconstruction of the 1992 source, and replaces only the layer that talked to
PC hardware — so the physics, the actors, the collision handling and the bugs
are Todd Replogle's. What is new underneath is an emulated EGA adapter, the
programmable interval timer, the keyboard controller, the PC speaker, and an
AdLib.

Six patches restore behaviour that would otherwise have been lost in
translation, each explaining the defect it fixes. One patch is a deliberate
change and says so: jump moved from ctrl to space, because ctrl with an arrow
key is a window manager shortcut on most systems now.

If you never heard the music as a child, that is because it needed an AdLib
card. The PC speaker effects everyone heard; the Bobby Prince soundtrack most
people did not.

Working

All three episodes · emulated EGA, unit tested · PC speaker effects, checked
against the game's own sound data · AdLib music through
ymfm · keyboard, including jump while
moving · saving and restoring · macOS, Linux and Windows

Not yet

No joystick. No frame-by-frame comparison against DOSBox, which is the honest
gap: the fidelity claims here come from inspecting the original data and the
game's own internal state, not from running the original side by side. MSVC is
untested — the Windows build is MinGW.

Credits and licensing

Cosmo's Cosmic Adventure, its artwork and its music are © 1992 Apogee
Software, Ltd. Episode 1 is included as the freely distributable shareware
release, unmodified and with its original DOS executable. Episodes 2 and 3 are
not included and are still sold.

This port's own code is MIT. Cosmore is MIT, © Scott Smitelli and contributors.
ymfm is BSD 3-Clause, © Aaron Giles. Full credits, including the game's original
authors, are in ATTRIBUTION.md.

The story of what it took to get here is in
docs/porting-notes.md.