Xevious was a genre-shaping game once. Now it's so dated, it barely even deserves a place in the genre it helped make.
Just like other 3D Classics, Xevious has awfully loud 8-bit music and sound supposed to induce nostalgia in the player. I cannot understand why Nintendo chose to do this with its 3D Classics. They are supposed to be remakes, not rehashes; but all that's remake-y about these games in the end is the 3D effect, which 3D Classics: Xevious makes surprisingly good use of. The 3D effect is very nicely done and there is a good sense of depth.
Xevious is an extremely early shoot-em-up. You play as a special sort of plane, supposed to shoot everything you see; mostly small round metallic objects. Some of them have red dots in the center which are supposed to be beacons. Overall, apparently there has been a very slight graphical update and it's not as 8-bit and rough as the other 3D Classics, but the graphics still could have been better. Nostalgia comes from the gameplay, not from the development team being cheap.
So how is the gameplay? Basic shoot-em-up gameplay. The phrase I would like to use is, 'basic shmup action,' but the extremely small number of enemies that somehow almost always manage to kill you even though you're not anywhere near their bullets, and the overall slow gameplay for a shoot-em-up makes it undeserving of that.
You can autofire by holding Y and drop bombs which hit into the targeting reticle always in front of your ship. You have three lives, and go through similar looking areas. There are some enemy thingies which have beacons and apparently (according to the included manual) warn other enemies of your appearance so you should kill them, but it doesn't really seem to make a difference except raising your score.
Overall, 3D Classics: Xevious is far too dated and unembellished for anyone except those who played it in the NES era to really enjoy. The development team didn't put a lot of effort into the remake. The 3D effect is the only update there is; apart from that, there's nothing new done. And considering it costs $5.99, it's not worth it except for the most nostalgic of gamers; considering much better games like Bloody Vampire, made with the 3DS in mind, cost less than it.