Out of this world.
I'm sure most people have played, or at least have heard of, Katamari Damacy. It's the game where you roll up progressively larger items until your ball is big enough to become a star. In a way, Orbital picks up where Katamari leaves off; you take control of a small object that collects space stuff until it's big enough to form its own solar system. At first glance, Orbital looks like a basic game, but once engaged with it you'll soon discover how complex and challenging it gets.
Here's how the game is played. At the start of a level, you begin with a very small planet that lazily travels through space. The goal is to collide with same-size objects to make your planet larger, granting you the ability to absorb larger objects. If your planet grows large enough, you can try to catch smaller objects in your orbit, creating moons. Colliding with objects that are too large or other dangerous items (like asteroids) will make your planet explode, costing you a life and throwing you back into space from whence you came. A sun will appear in the stage after collecting enough stuff, which you must capture in your gravity to complete the level. Points and extra lives are awarded based on completion time, planet size, number of satellites, and whether or not you captured the bonus moon that appears when the sun activates.
Getting around can be difficult, since you have no direct control over where your planet goes. You can enter the orbit of a planet to make it easier to get from point to point, but outside of that, the only way to alter the trajectory of your rock is to attract to or repel from other objects. I suppose it would be similar to how magnetic fields would interact on a planetary scale. If there's only one object to gravitate around, the system is easy and predictable. However, it becomes more complex when more stuff is in the area. Pushing away from something doesn't work well if there's another thing in the direction you want to go—you'd be repelling against that one, too. The strength of the effect is greater if there is more planet mass to attract towards or repel away from. Other factors which determine where you go are the speed at which you're moving and the mass of your own planet; something the size of Earth going just as fast doesn't exactly stop on a dime.
If you've played Super Monkey Ball, you'll have a better idea of how Orbital works. You know those SMB stages where you need to build up a lot of speed? Once you commit to a high velocity, it's very easy to lose a life after a little bounce or change in direction sends you flying off the platform. Orbital kind of works the same way, except the control you have over your planet is much more passive than a tilting board. And crashing could lose you three lives or more at a time as you pinball between planets. The game also has that “holy crap I need to get through that level?" mentality that some of SMB's advanced stages present. There's nothing like seeing a 10-wide stack of planets spinning around a central point like a lawnmower blade and realizing you need to shave planets off of the edges without the whole thing crashing in to you.
The 30 stages that make up Orbital are divvied up into six galaxies of varying themes. The first few stages are typical training cakewalks to help you get accustomed to the game’s concept. Later levels get crazy in a hurry. Stuff can move all over the place in a level, meaning a planet that you passed by a moment ago might be in a different place the next time around. Orbits of big planets can contain other planets (sometimes with their own orbiting hazards) or asteroid rings that do orbiting laps. A lot of times, you'll be required to find a way to get around all that peril without hitting any of it; something that becomes even more dangerous as you grow in size.
The game is entertaining because it's a genuine challenge to conquer each level and even more of a feat to grab the bonus crescent moon in your orbit, which is worth many points and extra lives. Unlike regular satellites, it bounces away if you collide with it. In addition, some levels put the moon in near-impossible places, like in the middle of an asteroid minefield or between a rock and a hard place where a perfect pass is required to obtain it. You usually only get one chance to nab the sucker, because missing the moon means it doinking away or you hitting one of the hazards guarding it.
Orbital has elements of puzzle games, adventure games, and even racing games, if you want to stretch the definition of each genre. I don't care what it is, really. All I know is the game is refreshingly good, and it's worth importing if your Game Boy Advance is being underused. Space is the final frontier, but let's all hope this is not the final time we see a space game like this.