The Gungriffon games are focused on piloting mecha: large, usually bipedal military vehicles. This game series refers to these machines as Armored Walking Gun Systems (AWGS). With the exception of the High-MACS design, the mecha in this series have a distinctly realistic design philosophy, which is more apparent in the more recent installments.
Source: Wikipedia, "Gungriffon", available under the CC-BY-SA License.
Gungriffon Blaze expands both its previous two games, coming out after Gungriffon 2, but being set in 2016, one year after the setting for Gungriffon 1 (The Eurasian Conflict in Japan).