The Final Zone series consists of three games: Final Zone, Final Zone II and a Genesis spin-off FZ Zenki Axis (known as Final Zone in the US, without the numeral). All three games are top-down mech shooters, though the third adopts an isometric angle and drops the dialogue scenes.
Due to the odd naming convention, the Genesis game is often mistaken as the first in the series with the TurboGrafx-CD game as its sequel. Rather, the first Final Zone (which was never released outside of Japan) is the original, the TurboGrafx-CD game is the sequel and the Genesis game is the third in the series.
Wolf Team, the development studio that would go on to create the Tales series and be bought by Namco Bandai, created the first Final Zone for Telenet. Because it was not particularly successful, Telenet gave the sequel to their internal studio Reno to develop. Meanwhile, Wolf Team would go on to work on the spin-off FZ Zenki Axis independent from Telenet.