An action-packed roller coaster thrill ride everyone who loves action should play.
The graphics on Gunstar Super Heroes are simply amazing. Multi-jointed mechs flow beautifully, backdrops look like they were taken straight out of a painting, character designs and animation are awesome and the weapon and explosion effects feel really lifelike. Little things like random particles and characters showing pain-stricken faces add to the rich atmosphere of the game. Scenes like act 1 of Moon 1 will leave you both slack-jawed and salivating for more. Even on the Game Boy Player, this game retains every bit of its luster. You will encounter a hint of slowdown here and there, but nothing that slows the pace dramatically or detracts from the experience.
The audio is an agglomeration of "Action Packed: Greatest Hits". Most of the time it fits the mood, whether is a serious cutscene or a silly natured battle, and invites you to play. Sound effects are right on the money, and the vocal bites are a nice and welcome addition.
I'll have to say right now: Gunstar Super Heroes is a difficult game. Sure, in Easy it's simple enough that anybody with decent gaming skills can beat it, but higher difficulties will test your mettle. It gets to a point that if you don't do things in a set pattern or if you make a single mistake, you'll most likely meet your doom. Amazingly, even after you die more times that you can count (it'll happen, trust me), it never gets frustrating, and it never feels as if the enemies, bosses or level designs get cheap in any way. In Easy, most enemies only serve as cannon fodder, but on higher levels, they defend themselves, become more tenacious and actually aim their weapons at you.
Of course, all of the above would be worth its weight in cow dung if the gameplay was no good. Fortunately, Treasure nailed that one too. Controlling either Red or Blue is a breeze. Once you discover all of their moves, pulling them off becomes second nature. Somehow, gunning your way through the game never once becomes old, thanks in part to the different and inventive gun types. The level designs are equally inventive, and all have their unique quirks, whether it's a rotating section where you need to rescue some chickies, or a game board-style area. Boss battles shine with their ingenuity, often requiring a good strategy or a specific weapon (or both, preferably) to take them down.
In short, this is an action game that no GBA owner should miss. If there's anything bad with it, is that the game runs a tad short. One play through (0-3 deaths) could take you around 1 or 2 hours, tops. But remember that you'll also play the game on 2 more difficulty settings, and with another playable character, so the playing time increases significantly. Also, there are no unlockable extras. None. Zip. Is it a shame? Maybe, but that doesn't make this game any less enjoyable. If you consider yourself an action player, you owe it to yourself to play this game.