Adventure Trilogy is one of the earliest semi-real time graphical adventure games for the Coco, and the first in a series by Nelson Computer Systems (later Softlaw); the 2nd and 3rd installments are Beyond the Cimeeon Moon and Fembots Revenge. You start with a fairly simple combat (comprising of 3 text commands) against two opponents. Then you descend below ground of a castle, seeking to find the "Eye of Dazmor;" and bring it back to the surface. This will let you get past the barrier holding you by the castle, and you can then go to the mountains, where you must deposit the Eye to the Forsaken Gulch. The game has movement controlled by arrow keys, and a limited set of 1 word commands (no VERB NOUN style text here!) to use. The play occasionally gets sluggish for some reason, and is fast most of the time (not sure why). The attempt at 3D graphics with descending stairs, etc. (not just simple hallways) is quite well done for this early on (it was released around mid-1981), and has fairly well done graphics for stairs, levers on walls, etc.
Title: Adventure Trilogy (originally called Adventure 3-Pak)
Author: Kevin Herrboldt and Tim Nelson
Publisher: Nelson Computer Systems, later renamed Softlaw Corp., later still through their ColorQuest division.
Released: July 1981 (first ad July 1981 80 Micro)
Requires: Color Computer 1/2/3, 16K cassette or 32K disk, Extended BASIC minimum.