You could think of it as a port of Crysis for the Apple II computer family

Find here a binary file which can be copied to a compatible Apple II disk.

The file suffix "#066000" is meant to indicate that it the Aux type file attribute should be kept as 066000 when copied to e.g., a ProDOS compatible environment with Ciderpress. Ciderpress understands suffixes of this format and should pick up the attribute automatically, but you might need to set it manually otherwise.

This is assembled using Merlin Pro assembler version 2.43. The source is all in one file, T.GR.asm. For example, from the main screen, you

• Press 'D' as needed to switch to the disk drive where the file is stored
• Press 'R' to choose the 'Read text file' menu option. This will take a few seconds.
• Press 'E' to enter the editor.
• Type 'ASM' and hit enter. It will output the assembled result.
• Type 'Q' and hit enter to return to the menu. Press 'O' to save the resulting binary. You may also want to save the source file using 'S'.
• Type 'Q' to quite back to Basic, assuming Basic environment is available.
• Run the program using BRUN GR (or replace 'GR' with the name you gave to the object file).

See the video of it in action: Link

This was borne out of a personal desire to learn more about programming 6502-on-Apple II. Ages ago I wrote Logo and Basic code for that platform but never in 6502 directly. This was made in a few days and tested using an emulator. I gave my disk image to a friend to run on real hardware. I expected this would shake out some inconsistencies between running on hardware and running on emulator, but there weren't any.

More info about what it was like working on this is in this blog post.