this is the NIAC MSMG-88. In the Black Age war game it acts as a concealable submachinegun, it also fulfills the role of a light weapon that could be used by light infantry such as commandos and assault troops.
The NIAC MSMG-88 ws originally designed to be a cheap alternative to the MSMG-56, however, the advent of the MSMG-80 series of the submachinegun almost scrapped the entire project. However, several years later the need for a weapon that could be easily showed and concealed arose, and the 88 of resurrected in the current form. The weapon has the unique ability to "fold" into a small box shape where it can be stored in any number of places from a briefcase to a thigh holster. the weapon in also surprisingly durable, and has become a favorite of drop troop and covert operatives.