Three levels of difficulty and an array of achievements (referred to as commendations) provide some replay value, although Challenge mode offers more incentive to keep coming back to Star Defense. Here you're pitted against a never-ending series of enemy waves, your high-scores posted to Facebook or Twitter. Opening this mode to include additional levels would be nice, as would incorporating new objectives and bonuses for going back and replaying levels in the campaign.
Neither diminish the satisfying strategic gameplay awaiting you in this stellar-looking title, though. Like a pinch to the neck of Mr Spock, Star Defense takes out competing tower defence games with gorgeous visuals and equally fine-tuned play.