Most games I play will open on the primary screen or the screen the launcher is on. DOTA always loads on the secondary screen. I've swapped ports rearranged everything, and it always launched on the secondary. However, if I move the dock to the "secondary" then it would open on my primary. It clearly is either forcing itself on the secondary monitor or avoiding the dock for some reason. It is far from ideal to have to switch my primary monitor before playing DOTA. If I leave the primary switched then other games that behave properly go to the "secondary". DOTA appears to be the sole poorly behaving app.