One Must Fall: 2097 is one of the best fighting video games from the 1990s programmed by Diversions Entertainment and eventually released as freeware.
You're going to need a DOS emulator. DosBox is the best choice.
One Must Fall: 2097 replaces the human combatants typical of contemporary fighter video games with large Human Assisted Robots (HAR). These HARs are piloted through a physical and mental link to the human pilots; however, this is merely a plot concept and is never shown on-screen.
Eleven HARs and ten selectable pilots are available for play, along with five arenas and four tournaments. The pilots vary in strength, speed, and endurance. Thus the many HAR/pilot combinations allow for large replay value.
Unlike in most fighting games of its time, the arenas (except one, the Stadium) contain hazards. For instance, one arena features spikes coming out of the darkness that can damage a robot.
The game has two main play modes: One-Player Mode, in which the company that markets the robots, World Aeronautics and Robotics (WAR), is holding a competition among its employees to decide who will be selected to oversee the establishment of the first Earth base on Jupiter's moon, Ganymede. The second mode is Tournament Mode, where HAR battles have become the premier source of entertainment for Earth and the player as a new competitor, must win prize money to improve the machine and ultimately become the World Champion.
Each HAR has three special attacks that can be discovered (except for Shadow and Nova, who both have four), along with a "scrap" and "destruction" move (similar to fatalities in Mortal Kombat) that can earn bonus points and, in some cases, unlock secrets.
Using destruction moves in the tournament mode in the higher difficulty levels sometimes results in the player being challenged by an unranked opponent. Defeating that opponent and using a destruction move on their robot occasionally yields secret components which can be installed on the players HAR, significantly improving the effectiveness of certain special moves and sometimes adding new ones.