For one reason or another Treasure decided on doing another Gunstar Heroes game. The original as I'm sure you're aware was the game that put Treasure on the map. You're probably also aware that Treasure does not do sequels. Yes there have been titles like Guardian Heroes Advance, Bangaioh DS, and that other title for Ikaruga(which is something like Radiant Silvergun Project 2). All of these games along with Gunstar Super Heroes do things differently enough to not be regarded as a sequel.
Gunstar Super Heroes is what I would refer to as a re-imagining. This is kind of similar to Smilebit's Jet Set Radio Future which is basically the first game but the stages were redesigned and the game design itself was changed drastically. To start with the game has more or less the exact same story as the first Gunstar and takes place over the same levels. Furthermore quite a few of the memorable bosses return though they've gone through various changes. Although all of the characters themselves are new within minutes you'll figure out everything that's going to happen next. This is also the last time I'll be referring to the original game as this is about all both titles really have in common.
While the game offers two selectable characters there's maybe one or two differences between the both of them. They both have access to three guns which are selectable at any time, a slide, a sort-of flying uppercut, a sword for close-range attacks, three flavors of jump-kicks(side, downward, and straight-down). While the Super Heroes lose the throw, block and weapon combinations the Heroes had access to they're still not hurting for abilities. The guns consist of a regular, homing, and explosive. These guns are self-explanatory and as a bonus special attacks are available. By while firing the player can access an extremely powerful cannon, a homing blast that stays on-screen for a short time, or a large explosion. This requires special energy which fills up by blasting enemies or collecting items. This is a lot to absorb and starting out can be rather tricky thanks to the GBA's limited buttons(the special weapons are accessed by holding down B and double-tapping R for example).
The purpose of all of these abilities is not in playing around but to destroy everything in a short amount of time. The closest similarity one can grasp from this game is Treasure's classic Alien Soldier. The stages are designed in a linear manner to the point where eventually you grasp which enemies must be destroyed for points while speeding through the ones that are worth nothing. The game uses more of the Contra/Metal Slug style of enemy attacks where instead of dealing with huge waves of bullets to weave between one simply has to be standing(or jumping) in the right spot at the right moment. The bosses are similar in that they have a limited number of attacks but are designed to slow down the player and possibly kill them if they're not paying attention when trying to better their time.
Make no mistake despite the storyline this game is very much designed for Score & Time Attack. Everything to the lack of customizable weapons to the near lack of experimentation points to Treasure going for a game that is pure and streamlined with one goal in mind. Treasure fans expecting elaborate boss battles with dozens of attacks are going to be very disappointed. Even Alien Soldier fans might not be able to get into this as this game simplifies the boss battles to a point where many of them are simply about getting to that spot and opening up a special weapon.
The game further differentiates itself from other titles in the Treasure library by changing up the goals of each stage. Simply running around and shooting enemies is rare in this game. You may find yourself riding on top of a ship while blasting away flying ships, but then you could be rescuing chicks from worms ala Sega's arcade game Flicky. While the goals change the mechanics and controls are for the most part the same so it's a pretty seamless transition.
The mechanics in this game are quite sound though at times it seems painfully obvious where the player should be standing to avoid damage. One moment that particularly stuck out to me was the stage where the Super Heroes face off against Seven Force for the first time. The player rides a vehicle that can jump from the floor to the middle of the screen to the ceiling. Upon reaching a vertical shaft the enemy flings bombs from above. These bombs travel in an arc at first but surprisingly they fall straight down either the floor, middle, or ceiling section(though I guess they're walls at this point but whatever). I guess at times it helps to easily figure out where one is supposed to be standing but c'mon this is just a bit too obvious.
The biggest fault with this game is that it is rushed. Aside from missing numerous things that have shown up in screenshots prior to the game's release(like a boss fight) there are numerous aspects that are either not properly balanced or completely unfinished. Some stages are near completely empty(stage 6 is literally just one long hallway without so much as a platform to jump on), the damage enemies can do varies wildly(many of the final bosses attacks do 1-5 points of damage yet many of the earlier enemies can do 10-30) and most of the bosses just feel unfinished and lacking(even considering the direction the game went).
Chief among these is the awful helicopter stage. I mentioned this earlier but it bears a closer look. This mercifully short stage consists of a huge helicopter through a vertical-scrolling area where the player has to destroy flying enemies while bombing ground-based targets. Hitting the ground targets is enough of an ordeal due to perspective and mechanics but the helicopter is not fit for dodging anything. In fact on the hard difficulty this is the hardest section of the game and yet it can be taken on as early as Stage 2.
Another unfortunate quality to this game is that too often it feels the need to remind the player that they are in fact playing a game based on Gunstar Heroes. Popular moments in the first game like when Colonel Red throws bots at the Heroes from his train are in this one as well. Although here Red is just standing there and somehow the bots manage to fall out on their own. Was this moment really necessary? It's one thing if Red was actively throwing the bots at the player but here it just looks cheap and pointless. While this game holds more than its fair share of surprises it's still too easy to predict what fans of the first game will see next and it becomes very predictable(it especially doesn't help when these retreads don't offer anything that takes advantage of the new elements, making them little more than interactive cutscenes.
Then again who knows at this point? It's plainly obvious the game was rushed so a large number of issues could have very well been fixed given enough time. Despite the problems it's still a functional and very playable game but it really could have turned out to be something special. Sadly at best it's competent and at worst(the final boss fight) it's just a huge mess that makes one believe that Treasure is overrated and quite possibly hasn't the faintest idea about good game design.