Night Slave

Night Slave is a side-scrolling action game very much inspired by Assault Suits Valken. The game starts off by introducing the members of your team, a group of mech-piloting girls from various countries who are assigned a new mission called 'Mission Night Slave'. You begin by investigating an enemy base but it's only a matter of time before the plot takes off, introducing more twists than you'll be able to keep count of -- or even see coming for that matter.

(From culture.vg review)