X is a Game Boy video game released in 1992 by Nintendo. Argonaut Software developed the game, and would go on to make a name for themselves when they assisted Nintendo in creating Star Fox. You control a ship named Space Tank VIXIV that travels through space to Tetamus II to stop an alien race from their progression towards taking over Earth.
There are eight levels that are all interconnected by tunnels that you'll fly your ship through. There are air and vehicular based segments in the game, and in both you'll have to keep an eye on your fuel and your missile count to make sure you don't run out of either. There are stations where you can refill both up, not to mention your overall health. Interestingly for a Game Boy game, X is a three dimensional video game, and was one of the first ever such games to be released on a portable device.