TList cycle through objects, not linear.

While 'NOT ESC'

cls

If Enemies=0; CreateWave()

//Grey Alien solution
If MoveDown= 1
    For Local e:TEnemy EachIn GameObjectList
         e.y :+ 20
    Next
    MoveDown = 0
End if
//-----------------------

For Local o:TGameObject EachIn GameObjectList
o.Update
o.Draw
Next

Flip 

CalculateDelta()

Wend

'Space Invaders v0.1
'Philip
'Start: 27 aug 2008

SuperStrict

'Declare files
Incbin "ship.png"
Incbin "missile.png"

'Declare constants
Global ScreenWidth: Int = 1024
Global ScreenHeight: Int = 768
Global ScreenColorDepth: Int = 32

'Screen resolution
Graphics ScreenWidth, ScreenHeight, ScreenColorDepth

'Hide the Mousepointer
HideMouse()

'Declare types

'Default for all Gameobjects
Type TGameObject

	Field x:Float, y:Float
	Field speed:Float
	Field life: Int
	Field img:TImage
	Field xmargin:Int, ymargin: Int

	Method Draw() 	
		DrawImage(img, X, Y)
	End Method
	
	Method Update() Abstract

End Type

'Thats you, the player
Type TPlayer Extends TGameObject
	
	Field FireDelay: Int
	Field TempDelay: Int = 0
	Field Weapon: Int = 0
	Field WeaponSpeed: Int = 6

	Function Create:TPlayer(px:Int, py:Int, pspeed:Int, plife:Int, pdelay:Int, pimg:String)
		Local P:TPlayer = New TPlayer
		P.x = px
		P.y = py
		P.speed = pspeed
		P.life = plife
		P.FireDelay = pdelay
		P.img = LoadImage(pimg)
		P.xmargin = ImageWidth(P.img) / 2
		P.ymargin = ImageHeight(P.img) / 2
		MidHandleImage(P.img)
		ListAddLast GameObjectList, P
		Return P
	End Function	

	Method Update()
		
		If KeyHit(KEY_SPACE)
			Player.Shoot()
		EndIf

		If KeyHit(KEY_UP)
			Player.SwapWeapon()
		EndIf
	
		If KeyDown(KEY_LEFT)
			Player.x :- (Player.speed * AlphaTime)
		EndIf
	
		If KeyDown(KEY_RIGHT)
			Player.x :+ (Player.speed * AlphaTime)
		EndIf
		
		If x < xmargin ; x = xmargin
		If x > ScreenWidth - xmargin ; x = ScreenWidth - xmargin
		TempDelay:- 1
	End Method
	
	Method SwapWeapon() 
		Weapon:+ 1
		If Weapon = 2; Weapon = 0
	End Method
	
	Method Shoot()  
		If TempDelay < 0
			Select Weapon
				Case 0
					WeaponSpeed = 4
					FireDelay = 15
				Case 1
					WeaponSpeed = 2
					FireDelay = 8
			End Select
			Local S:TBullet = TBullet.Create(x , y - ymargin , - 1 , WeaponSpeed , 1 , "incbin::missile.png")
			TempDelay = FireDelay
		EndIf
	End Method	

End Type

'The default for all Enemies
Type TEnemy Extends TGameObject
	Field StepYLocal:Int =0
	
	Function Create:TEnemy(ex:Int, ey:Int, espeed:Float, elife:Int, estepylocal:Int, eimg:String)
		Local E:TEnemy = New TEnemy
		E.x = ex
		E.y = ey
		E.speed = espeed
		E.life = elife
		E.StepYLocal = estepylocal
		E.img = LoadImage(eimg)
		E.xmargin = ImageWidth(e.img) / 2
		E.ymargin = ImageHeight(e.img) / 2
		MidHandleImage(E.img)
		ListAddLast GameObjectList, E
		Return E
	End Function	

	Method Update() 	
		x :+ ( (EnemyDir * speed) * AlphaTime)
		If x < xmargin Or x > (ScreenWidth - xmargin) 
			EnemyDir :* - 1
			StepY = 1
		EndIf
	End Method
	
	Method UpdateY() 	
		y :+ (StepYLocal * AlphaTime) 
		speed:+ ((speed/10) * AlphaTime)
	End Method
	
End Type

'The default Bullet
Type TBullet Extends TGameObject
	Field direction: Int = 0

	Function Create:TBullet(bx:Int, by:Int, bdirection:Int, bspeed:Int, blife:Int, bimg:String)
		Local B:TBullet = New TBullet
		B.x = bx
		B.y = by
		B.direction = bdirection
		B.speed = bspeed
		B.life = blife
		B.img = LoadImage(bimg) 
		B.ymargin = ImageHeight(B.img) / 2 
		B.y :- B.ymargin
		MidHandleImage(B.img)
		ListAddLast GameObjectList, B
		Return B
	End Function

	Method Update() 
		y :+ ( (direction * speed) * AlphaTime) 		
		If Life <= 0 Or x < 0 Or x > ScreenWidth Or y < 0 Or y > ScreenHeight
			GameObjectList.Remove(Self)			
		End If 	
	End Method
	
End Type

'Declare placeholders and globals
Global GameObjectList:TList = CreateList() 
Global Player:TPlayer = TPlayer.Create(ScreenWidth/2, ScreenHeight-30, 4, 3, 3, "incbin::ship.png")

Global LastTime:Int = MilliSecs()
Global AlphaTime:Double

Global Enemies:Int = 0
Global EnemyDir: Int = 1
Global StepY:Int = 0

'Main loop
While Not KeyDown(Key_Escape)

	Local o:TGameObject
	Local e:TEnemy
	
	Cls

	If Enemies = 0; Wave()

	For o = EachIn GameObjectList
		o.Update()  
	Next
	
	'Possible Y update
	If StepY > 0
		For e = EachIn GameObjectList
			e.UpdateY()
		Next
		StepY = 0
	EndIf
	
	'Draw actual	
	For o = EachIn GameObjectList
		o.Draw()
	Next
			
	Flip

	DeltaCalculate()

Wend

GCCollect()
End

Function DeltaCalculate()
	Local CurTime:Int = MilliSecs()
	AlphaTime = (CurTime - LastTime) / 10.0
	LastTime = CurTime
End Function

Function Wave()	
	EnemyDir = 1
	For Local EnemyRow:Int = 1 To 8
		For Local EnemyColumn:Int = 1 To 5
			Local Enemy:TEnemy = TEnemy.Create(150 + (50 * EnemyRow) , 10 + (50 * EnemyColumn) , 0.1, 20, 1, "Incbin::ship.png")
			GameObjectList.Addlast(Enemy) 
			Enemies:+ 1
		Next
	Next
End Function