Adult PC Game: Kyonyuu Onna Shikan Sennou Saimin by Lune Archive

Hundreds of years have passed since humanity began to immigrate into space. Humanity has spread too far and created their own agendas and interests. Soon enough, war occured with the usage of battleships and robots.
The protagonist was once an excellent test pilot. Now, he is a humble mechanic after an accident forced him to be transferred.
Unable to quit the army, he spent his days aimlessly. Soon, he was assigned to a newly established battleship that focuses on reconnaissance and collecting data.
However, during maintenance, he discovered a secret hidden in the ship. One that caused him to shake in anger. And the words that appeared in front of him.
'Please enter what you want me to do'.
That changed the fate of the protagonist in the future.