Metroid Zero Mission is actually a remake of the first Metroid game that was released in 1986 during the NES era. Being that this a remake of the original, pretty much everything should be the same right? Well, no. Nintendo decided to make basically a brand new game with the same, slightly expanded, storyline.
The game does a very good job of fleshing out the story of Samus Aran's debut into the video game world with small cutscenes thoughout the game. In the original Metroid, all you got to go on was 'Go to Zebes and defeat Mother Brain'. The game starts off the same as before, with Samus having arrived just inside the entrance to Crateria. You then progress around the map discovering new items for Samus to use in her quest to defeat Mother Brain. As is the trademark of all Metroid games, you much discover various power ups in order to help you progress. Starting with the Morph Ball, moving on to missiles, bombs, super missiles, energy tanks, new beams, etc, new paths and areas become available to you to explore as you increase your abilities. Previously locked doors can now be opened with the right weapon, walls can be broken with the help of a certain items, and so on. There is always reason to traverse each area in the game multiple times to gather as many of these powerful upgrades as you can in order to attempt a 100% collection rate.
There are a few big changes in Zero Mission from the original game. One if these is the way to replenish energy. In Metroid you had to find another energy tank or kill monsters and pickup the energy units they left behind. This would lead to long and arduous runs just to prepare for a boss fight. In Zero Mission, the various Chozo statues you encounter double as refilling stations and upgrade protectors/guides. When you roll as the morph ball into the statue's hand, it refills your energy/missiles/aux items to full. In several cases the statues will point you in the direction that you need to go by providing a blip on your map. This adds a sense of direction to proceedings so you won't be wandering around for ages not knowing where to go. That said, it should have been able to have been turned off as many Metroid veterans perfer not knowing where to go, discovering the game on their own.
Control is on par with Metroid Fusion, with Samus's movements and abilites being near identical. The bosses, whilst visually well designed and great to look at, are actually rather easy when compared to Fusion, which is a real shame as many would argue that the challenge was Fusion's strongest asset. If you figured out what they're going to do, and have enough rockets, the bosses only take a minute or two to overcome. The best part of the gameplay, in my opinion, is after Mother Brain is defeated where (For people wanting to avoid a slight spoiler please skip the rest of this paragraph) Samus has no abilities and no suit. With only a stun laser for protection you find yourself running and taking cover from enemies quickly, and needing to keep hidden was probably the most challenging part in the game.
There are many extras included in this game - one of the best is the original Metroid for NES. The game runs perfect, and is probably more challenging than Zero Mission. Definately give that a try if you've never played the NES version before. Another extra lies in the ability tolink up to Metroid Fusion, allowing to download a gallery of pictures viewable on your Game Boy. Metroid: Zero Mission's greatest downfall though is its length. It can be completed rather quickly, in 3/4 hours for an average player.
The only way to rate the visuals is in comparison with Metroid Fusion. In this area, the game is splendid. There is great use of sprite-scaling, and very detailed backgrounds which are often overlooked in your mad rush to eliminate all the enemies in the room. Lava and water effects are done well too. The numerous enemies are all wonderfully designed with each having its own attack, all of which is animated extremely smoothly. The bosses are HUGE, with smoothly animated moving parts and just their general designs look amazing. The one thing I was rather impressed with were the cut screens. The cut scenes give a much clearer sense of what was going on. Still pictures are presented in a slideshow and feel almost like reading a comic book. If you've played Metroid Fusion, you know the sound is amazing and this game is the same way. The soundtrack is basically remixed songs from the old Metroid, but they sound much better, especially though headphones as to get the very best experience from this game, you need to be listening in stereo. Sounds are crisp, and as alien-like as you'd expect them to be.
Metroid: Zero Mission is a GBA must have. Yes, it may be a bit short. Yes, it may be too easy (though 2 extra difficulty settings makes things a little tougher second time around), but for the sheer experience that the game provides and the exeptional trademark Metroid level design, it's not a game to be overlooked. If you've never played a Metroid game before, this is the best place to start.