the most simple fly menu ever open source

 UserInputService = :()
 RunService = :()
 Players = :()

 player = Players.LocalPlayer
 character = player.Character  player.CharacterAdded:()
 humanoid = character:()
 rootPart = character:()


 flying = 
 flySpeed = 
 flyDirection = .(,,)
 bodyVelocity


 screenGui = .()
screenGui.Name = 
screenGui.Parent = player:()


 mainFrame = .()
mainFrame.Size = .(, , , )
mainFrame.Position = .(, , , )
mainFrame.BackgroundColor3 = .(, , )
mainFrame.BorderSizePixel = 
mainFrame.Parent = screenGui
mainFrame.Active = 
mainFrame.Draggable = 


 title = .()
title.Size = .(, , , )
title.BackgroundColor3 = .(, , )
title.BorderSizePixel = 
title.Text = 
title.TextColor3 = .(,,)
title.Font = .Font.SourceSansBold
title.TextSize = 
title.Parent = mainFrame


 flyButton = .()
flyButton.Size = .(, , , )
flyButton.Position = .(, , , )
flyButton.BackgroundColor3 = .(, , )
flyButton.BorderSizePixel = 
flyButton.Text = 
flyButton.TextColor3 = .(,,)
flyButton.Font = .Font.SourceSansBold
flyButton.TextSize = 
flyButton.Parent = mainFrame


 speedLabel = .()
speedLabel.Size = .(, , , )
speedLabel.Position = .(, , , )
speedLabel.BackgroundTransparency = 
speedLabel.Text = 
speedLabel.TextColor3 = .(,,)
speedLabel.Font = .Font.SourceSans
speedLabel.TextSize = 
speedLabel.TextXAlignment = .TextXAlignment.Left
speedLabel.Parent = mainFrame


 speedSlider = .()
speedSlider.Size = .(, , , )
speedSlider.Position = .(, , , )
speedSlider.BackgroundColor3 = .(, , )
speedSlider.BorderSizePixel = 
speedSlider.Text = 
speedSlider.Parent = mainFrame

 sliderFill = .()
sliderFill.Size = .(flySpeed/, , , )
sliderFill.BackgroundColor3 = .(, , )
sliderFill.BorderSizePixel = 
sliderFill.Parent = speedSlider


  ()
     flying   
    flying = 
    flyButton.Text = 
    bodyVelocity = .()
    bodyVelocity.MaxForce = .(, , )
    bodyVelocity.Velocity = .(,,)
    bodyVelocity.Parent = rootPart


  ()
      flying   
    flying = 
    flyButton.Text = 
     bodyVelocity 
        bodyVelocity:()
        bodyVelocity = 
    


flyButton.MouseButton1Click:(()
     flying 
        ()
    
        ()
    
)


 dragging = 
speedSlider.InputBegan:((input)
     input.UserInputType == .UserInputType.MouseButton1 
        dragging = 
    
)

speedSlider.InputEnded:((input)
     input.UserInputType == .UserInputType.MouseButton1 
        dragging = 
    
)

speedSlider.InputChanged:((input)
     dragging  input.UserInputType == .UserInputType.MouseMovement 
         relativeX = .(input.Position.X - speedSlider.AbsolutePosition.X, , speedSlider.AbsoluteSize.X)
         percent = relativeX / speedSlider.AbsoluteSize.X
        flySpeed = .(percent * )
         flySpeed <   flySpeed =  
        sliderFill.Size = .(percent, , , )
        speedLabel.Text = ..flySpeed
    
)


 moveVector = .(,,)
 keysDown = {}

UserInputService.InputBegan:((input, gameProcessed)
     gameProcessed   
     input.KeyCode == .KeyCode.W  keysDown.W =  
     input.KeyCode == .KeyCode.S  keysDown.S =  
     input.KeyCode == .KeyCode.A  keysDown.A =  
     input.KeyCode == .KeyCode.D  keysDown.D =  
     input.KeyCode == .KeyCode.Space  keysDown.Space =  
     input.KeyCode == .KeyCode.LeftControl  keysDown.Ctrl =  
)

UserInputService.InputEnded:((input, gameProcessed)
     input.KeyCode == .KeyCode.W  keysDown.W =  
     input.KeyCode == .KeyCode.S  keysDown.S =  
     input.KeyCode == .KeyCode.A  keysDown.A =  
     input.KeyCode == .KeyCode.D  keysDown.D =  
     input.KeyCode == .KeyCode.Space  keysDown.Space =  
     input.KeyCode == .KeyCode.LeftControl  keysDown.Ctrl =  
)


RunService.RenderStepped:(()
     flying  bodyVelocity 
         camCFrame = .CurrentCamera.CFrame
         direction = .(,,)
         keysDown.W  direction = direction + camCFrame.LookVector 
         keysDown.S  direction = direction - camCFrame.LookVector 
         keysDown.A  direction = direction - camCFrame.RightVector 
         keysDown.D  direction = direction + camCFrame.RightVector 
         keysDown.Space  direction = direction + .(,,) 
         keysDown.Ctrl  direction = direction - .(,,) 

         direction.Magnitude >  
            direction = direction.Unit * flySpeed
        

        bodyVelocity.Velocity = direction
    
)