One Must Fall: 2097

Released in 1994 by Epic MegaGames, 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 it is never shown on-screen, nor does it factor in to gameplay. Eleven HARs and ten customizable 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 wall that can damage your robot, and one has a floating sphere that, when struck, triggers a fireball from the floor under your opponent.

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, set three years after the first tournament, where HAR battles have become the premier source of entertainment for Earth and you, a new competitor, must win prize money to improve your machine and ultimately become the World Champion.

The game was later patched to include multiplayer support. On February 10, 1999, the game was declared freeware by the developers.

Source: Wikipedia, "One Must Fall: 2097," available under the CC-BY-SA License.