The below code limits movement to a single axis giving preference to the y axis. Arrange it with left and right first and you will give preference to the x axis.
; I make UP, DOWN, LEFT, RIGHT global variables that can be defined as any key. ;This is great as it allows for user defined keyboard set ups. If keydown(UP) Then ; add code here to move object accordingly ElseIf keydown(DOWN) Then ; add code here to move object accordingly ElseIf keydown(LEFT) Then ; add code here to move object accordingly ElseIf keydown(RIGHT) Then ; add code here to move object accordingly EndIf