Having completed several missions I find it rather distracting to have "Get your first mission" generously slathered across most of my would be visible play area.
This so far is the best 'Watch the enemies walk casually by your defending towers' game I have yet to play. Oh sure I can purchase towers but if you call that playing then I think I might have the wrong idea of what a game is.
Just an observation. Defending towers might want to shoot in order to defend. But that might just be me.
Wait. Nope. Looks like it's the rest of the world too.