Similar to Elite, Mercenary gives you a wonderful sense of freedom and being able to explore the self-contained world in astounding detail. You will spend most of your time exploring the planet, both above ground and below ground, in all the 3D wire-frame glory. Many locations in the city are connected by an intricate network of underground tunnels, and finding your way around these mazes takes up a good portion of the game. In addition to flying around in your ship, you can also wander around the rooms from a first-person perspective, collecting objects that may be useful (such as the keys) or useless.
What makes Mercenary a wonderful game is that, like Elite, the game gives you a lot of freedom to explore. There is no time limit, and it is very hard to die. Similar to other huge, open-ended games, Mercenary has its own share of interesting secrets and even a great sense of humor. You can, for example, pick up a chunk of cheese and use it as a plane (why? Because it is a "Kraft"...) Whenever you feel like following the main plot, the in-game computer Benson is there to give you helpful hints from time to time so you won't feel too lost.
With great gameplay, reasonable physics model, and a wonderful self-contained world that offers countless hours of fun discoveries, MDDClone is a faithful rendition of an 8-bit classic that was never officially released for PC. Definitely a must-play for all Elite fans, and keep checking the official site below fore news, because the author plans to include the third and final game in the trilogy called Mercenary III in the package sometime in the future ;) (and this page will be updated when that happens). The latest version even has optional corrections of bugs in the original game :) Two thumbs up, way up!