Adult PC Game: Mech Academy - v1.0.0. by Space Samurai Games Archive

Mech Academy is an adult visual novel based on multiple-choice decisions. The player will take on the role of the protagonist in this story and meet different characters and try to develop a relationship with them. The player's decisions will have an impact on the evolution of the story.
"It is the year 2175, and you are the pilot of a Mech Guardian. These are giant war machines built to defend Earth from the Noxa, a ruthless alien race intent on conquering your planet. However, you do not belong to this period; you are actually Lieutenant Knight, a highly decorated soldier who lived in the 1970s. Because of a mysterious experiment, you have been catapulted two centuries into the future. Everything is new and complicated for you. Your world, the society you grew up in, is profoundly different from the one you are in now."

Mech Academy - v1.0.0. by Space Samurai Games Gameplay Preview