The bounce function has the following line:

bounce = difference;

Which should be:

bounce += difference;

Also, I’m not sure why, but the bounding box for the ship in MarsBaseOneWorldBuilder/mars_base_one/src/main.rs is commented out, so it passes through walls until uncommented:

  spawn_image!(
    assets,
    commands,
    "ship",
    0.0,
    200.0,
    1.0,
    &loaded_assets,
    GameElement,
    Player,
    Velocity::default(),
    PhysicsPosition::new(Vec2::new(0.0, 200.0))//,
    //ApplyGravity(0.2),
    //AxisAlignedBoundingBox::new(24.0, 24.0)
  );