Abandonware DOS title

The most popular Engine: Z-machine games

The Z-machine was developed by Infocom and used in its interactive fiction games. Z-machine is a virtual machine that allows a developer to easily develop text-adventures for multiple platforms without much hassle. A number of interpreters exists so you can play both old and new text adventures on dead platforms as well as recent ones: Glulx, Inform, TADS, etc.
deadline-2

Deadline

DOS1982 Infocom
enchanter-splash

Enchanter

DOS1983 Infocom
the-witness-01

The Witness

DOS1983 Infocom