A hard and entertaining strategy game.
Gameplay:
You and your opponent each start off on a small island or archipelago. As mentioned above, you have to wipe out the enemy with your weapons. This is not an easy task, even if your weapons are fully upgraded (Double Missile / Golden Metal Marine). It's very hard to get through the enemy defenses and defend your own base(s) at the same time.
If the game lasts long enough, you may be able to build the anti-matter-weapon, the mightiest weapon available in the game. However, this weapon needs much space and fuel and takes long to build, thus making it extremely vulnerable for enemy attacks. The enemy can easily find and destroy it while it's being constructed.
To defend your base, you must build Gun Pods (against Metal Marines) and Anti Air Missiles (against enemy Missiles). If you don't build enough defensive structures, you will lose very fast.
It's very difficult to win in the later stages, mainly because of these aspects:
1. You usually don't have much money. You can get more money by building Supply HQs, but they cost a considerable amount of money themselves.
2. You usually don't have much fuel. You need fuel to attack the enemy. Without fuel, missiles and metal marines can not fly to the opponent's island.
3. The enemy has much better weapons and much more fuel and money than you at the beginning. If he spots and destroys your main base while you're still building up a defense, you might want to restart the mission.
I wouldn't recommend this game to people who get angry easily since it'll be necessary to play stages several times before you can finally find an exploitable weak spot in the opponent's initial defense. That's especially true for the later levels (there are 20 overall).
Graphics:
Decent graphics, but not perfect. The enemies look very cool when they appear on the viewscreen before each mission.
Sound:
The music is good, but gets repetitive very fast in my opinion due to a lack of tracks.
Sound effects are good, too.
Value:
Some stages are very funny to play through again. You gan get to every stage you want since this game uses passwords. It's very entertaining to play through the game again, too - at least for me.
Overall, what can I say? This is one of my favourite SNES games. Try it, maybe you will like it, too. And as said before: Please don't get this game if you're a choleric person. It may get annoying sometimes.