class World {
    World(int width, int height, int stepsPerSecond) {
        _grid = new Grid(width, height);
        _mover = new UnitMover(_grid, Pathfinding.Find);
        ...
    }
    ...
}

static class Pathfinding {
    public delegate bool OccpiedPred(Int2 cell);

    public static List<PathSegment> Find(OccpiedPred occupied, Int2 from, Int2 to) { ... }

    ...
}

class UnitMover {
    public delegate Path FindPath(Pathfinding.OccpiedPred occupied, Int2 from, Int2 to);

    public UnitMover(Grid grid, FindPath findPath) { ... }

    ...
}