Metal Max (メタルマックス?) is a 1991 vehicle combat role-playing video game developed by Crea-Tech and published by Data East for the Nintendo Famicom exclusively in Japan on May 24, 1991 and later re-released on the Wii Virtual Console on April 27, 2010. It is the first of the Metal Max series. Metal Max is set in a futuristic post-apocalyptic world, where the surviving humans cluster in underground villages and ruins while "monster hunters" fight the monsters and outlaws outside. The game got a sequel, Metal Max 2, and was remade for the Super Famicom as Metal Max Returns.
Metal Max was an early example of an open-ended and non-linear role-playing video game. It lacked a predetermined story path, but the player was instead given the choice of which missions to follow in whatever order while being able to visit any place in the game world. The ending can be determined by the player, who can alter the ending through their actions, complete the game at almost any time, and can continue playing the game even after the ending.
The character classes, such as a mechanic or soldier, could be chosen for the player characters, who would fight in turn-based battles either on foot or using tanks. The player could create tanks, customize and make a variety of modifications to them, remodel and enhance each part, strengthen the defense, repair damaged parts, and give them more shells.
Source: Wikipedia, "Metal Max", available under the CC-BY-SA License.