Troff II

Troff II is a Snake-inspired game (released before QBasic's Nibbles) which features decent enough gameplay and controls, but is hampered somewhat by the difficult computer AI opponent. The goal here is to collect enough points by collecting items (and avoid losing points by running into things) to meet the level objective and move on. There are some options that can be set from the main menu, but the game basically plays like Snake except with a heavier emphasis on collecting stuff. It does come with source code in Turbo Pascal 5.5 if you're into that sort of thing.