Robo Pit is a robot fighting game released in 1996 for PlayStation and Sega Saturn. The game was developed by Altron and published by Kokopeli Digital Studios outside Japan. A sequel, Robo Pit 2, was released in Japan on PlayStation in 1997 and 2003 in Europe and North America.
The rules are, build a robot and then try to fight your way to the top in arenas that are square in shape. There are many different types of arenas and the time of day can vary.
There are various types of weapons which include The Axe, Lips, Sword, Missile and Claws as well as many more. As you fight your way to the top there are bosses you will fight along the way.
Source: Wikipedia, "Robo Pit", available under the CC-BY-SA License.