Cave Walker is a sequel to the earlier, Spectral produced cartridge from Radio Shack called Downland. Cave Walker is much larger (at least 25 different caverns, as opposed to Downland's 10), and is more complicated. It also was OS-9 based, and had some special color options for the Coco 3, if run under OS-9 Level II. It also allowed one to save several games in progress, and featured a practice mode (although, one could not get into 9 of the caverns if playing in this mode).
Cave Walker also was different in that it actually used the analog joysticks as analog; the more you moved the joystick to the side, the further you would jump when you hit the fire button. It was also one of the earliest games that had instructions on how to install it on a hard drive (along with Spectral/Tandy's Interbank Incident).
Title: Cave Walker
Author: ??? (Spectral Associates)
Publisher: Radio Shack/Tandy
Released: 1986
Requires: Color Computer 1 or 2: 64K RAM, disk drive, OS-9 Level I (included), or Color Computer 3: 128K RAM, disk drive, OS-9 Level I version 2.0 (included) or OS-9 Level II. Joystick for both versions.