The Yellow Moon's School: The Ghosts Day

The Yellow Moon's School: The Ghosts Day is a top-down shooter game in which you
must shoot ghosts and destroy them to save the school.

You control a student with a gun and have to shoot and eliminate hordes of Ghosts
while avoiding contact with them. Some ghosts have guns and will shoot you.

When you destroy hordes, a new stronger horde will appear, so you may have to
upgrade to win.

When you kill a ghost, you earn money. Use the money to upgrade and get stronger.