starts, after a brief explanation by your commanding officer, in a VR training session where you are taught the basics of flying your SHN Fighter. After that, you head off into your first galaxy, appropriately named Alpha Galaxy. In each galaxy, you must get past three worlds.
You have three lives to use in order to get through each of the galaxies; once you have used a life, it will stay lost until you defeat that galaxy. Though you can encounter the worlds within the galaxy in any order, they seem to be laid out from easiest to hardest (left to right) anyway. I guess this is to appeal to different people's play styles. If you want to tackle the hardest and most grueling world first, then by all means do.
The game has three basic modes: Story Mode, Arcade Mode and Challenge Mode. Story Mode is, as the name suggests, the mode that takes you through the plot. Once you beat a world, you are given a password; this password allows you to return to this point in the game instead of using a saved game system.
The other two modes have an interesting 'online' feature that reflects what some other online games are doing these days. In Arcade Mode, you play through each level that you have unlocked. Here you only have one life, and upon defeating that level, you will receive a code. With this code you can go to Iridion II's web site, www.iridion2.com, and submit it to see how you compare to everyone else around the world.
In Challenge Mode, which is unlocked after completing the Story Mode, you go up against all of the bosses, one after another, and after winning there you are given another code that you can post on Iridion's site.
There is also a Jukebox feature, unlocked after the Challenge Mode, and a Gallery feature, unlocked after the Story Mode.
As far as in-game content is concerned, before starting a flight, you must choose one of six different weapons, each with different spray patterns. While in the world, your weapon can be upgraded three times, once to add satellites that release two more beams, and two more times to make those beams more powerful. In the level, you may also be able to pick up other weapons and switch between them at your leisure.