Metal Slug 4 is certainly the weakest of the series so far with rehashed levels and same-old baddies. You get the option of a new playable character (or at least it looks like someone new) but what is the point of having four separate, playable characters when they all have the same ability? It's not even like they come with different guns. And why do you get a life bar when only one bullet kills you?
This game does give you the bonus of ONE new weapon-the double machine gun. But every time you pick it up someone will come along and kill you. Honestly, these games are so damn hard. It's fine if you have infinite continues or an infinite supply of quarters but how on earth they expect you to survive to the end of the level with all your stats intact is beyond me. They should remain until your next continue instead of vanishing with every life lost.
Yes, the level design is brilliantly detailed and the humor is still there but it's too hard and it's getting mighty damn repetitive. Give us something new for Metal Slug 5 please.