I have been a fan of the Metroid series ever since I played Super Metroid on the SNES. So, purchasing Metroid Prime 3: Corruption was an obvious decision. I think that the game was pretty good. The elevation of the Grapple Beam to the position of being a major game play element was well executed for the most part. However, not all of the weapons and tools in the game were created equally. During my play-through of the game, I made one major discovery:
The Seeker Missile does a very poor job as a weapon.
During the entire course of Metroid Prime 3, I only used the Seeker Missile two or three times in an actual combat situation. The biggest problem facing the Seeker Missile is that it is a weapon designed to target up to five enemies at once in a game where Samus Aran is usually fighting enemies in groups of 3 or less at a time. There are only a handful of enemy groups in the game that are larger than three:
1) The large swarms of small, swarming enemies, such as the Pirate's walking mines. Most of these enemies are non-hostile, and the ones who are tend to advance too quickly to lock on to with all five missiles. In any case, spamming beam fire works well against these, and consumes less ammo.
2) The Tinbots and Steambots in Elysium. However, all of the Steambots are dead by the time Samus gets the Seeker Missle, and the Tinbots are easy to fight with other weapons.
3) The large swarm of six warping Metroids on the Valhalla. However, these enemies all but immune to missiles except for the brief moment where they pull back and charge at Samus. It is more reliable to take them down with a barrage of Beam fire.
While there are places where it is possible to get good use out of the Seeker missile, there are usually other strategies that work just as well if not better. This problem is exaggerated by some problems with the weapon itself that tend to discourage the player from using it:
1) Missiles have finite ammo. If faced with the choice of using up a limited resource or using an alternative strategy, most people would go for the alternative strategy, unless the one that uses up limited resources are significantly better.
2) The Seeker missile wasted 1 missile whenever I first pressed the missile button down to charge it up. In order to not waste a missile, I was forced to charge the beam temporarily, and then quickly hold down the missile button as the beam fired.
3) I never got the "lock onto one enemy more than once" ability of the Seeker Missile to work.
Because the Seeker missile never stood out as superior to other weapons in any specific situation, it simply was not a good weapon. In order for a weapon to really be seen as valuable by a player, it needs to give the player a significant advantage compared to other weapons in the same game under some circumstances.
The Ice Missile from the same game is a good example of this concept. On the second planet of the game, Samus Aran fights enemies such as the Reptilicus and Warp Hound, which are very resistant to normal missiles and beam shots, and can be aggressive attackers. However, the Ice Missile that is obtained on that planet makes them much easier opponents. It takes only two or three Ice missiles to kill one of these enemies, and the Ice missile slows them down, making them easier to hit and weakening their offense.
Because the Ice Missile has that effect, it makes the player start to think: "How did I ever live without this?" That kind of thought is what makes a weapon a good weapon.
There are a couple of things the developers of Metroid Prime 3 could have done to make the Seeker Missile more worthwhile. Most of these suggestions involve adding enemies that make the Seeker Missile a better choice for fighting against them. Unfortunately, most of the enemies and puzzles that require the Seeker Missile in Metroid Prime 3 are obvious and feel forced.
1) There are flying bug enemies on the second planet that are best fought using missiles simply because they are too fast and evasive to hit with beam shots. However, they only appear in packs of two or three at most. If they came in larger swarms of six or more, then the Seeker Missile would be an attractive option for fighting them.
2) Enemies that are more dangerous if attacked one by one. For example, a bunch of robots that become aggressive as soon as one of them is attacked. Alternatively, a group of enemies that gain more powerful attacks each time one is destroyed. In that case, the best option for fighting them would be to destroy all of the enemies at once.
With some additions like these, the Seeker Missile could have been a much more significant part of Metroid Prime 3.