EDF! EDF! You'll be shouting that the entire time your playing Earth Defense Force.  This game is one of the most frantic shooters I have ever played.  The missions are very repetitive but its still a blast, especially if you have a few friends.  There are four different classes in EDF which are Trooper, Battle, Jet, and Tactical I believe.  It's also a blast just destroying buildings. The visuals aren't the greatest but they're definitely not the worst either.  EDF isn't very long either I think there is a total of 15 missions.  There is also Survival mode which is where you can see how long you can survive against waves of ravagers, hectors, etc. Earth Defense Force: Insect Armageddon is definitely a game worth checking out.