In Symphony, you control a space-ship in a fixed region and shoot down enemy crafts. The levels are generated by the music - more frantic moments generate more enemies. The stock music is mainly electronic, some classical sounding compositions, and some slightly rocky songs. You can choose your own music, as long as it is a couple of minutes long.
As part of the story, every so often, a boss appears. Defeat several bosses and this unlocks the next difficulty mode. Many of the bosses are similar.
You ship can often take a few hits which means you lose your guns, pick up power-ups to restore. Sometimes you can only take one hit though. I wasn't sure why this was; presumably it's when your ship gets hit centrally. You respawn with a score penalty.
Most enemies don't fire, but the challenge is to dodge them. When they do fire, it can be hard to see the bullets. Sometimes the amount of particles obscure your vision, but they also have a tendency to fire at almost point-blank range. The enemies, particles and background are all the same colour. The colour changes at intervals, but they all change at the same time. I felt this caused a majority of my deaths; since enemies didn't stand out enough against the background or particles. This severely reduces the enjoyment in the game. Why couldn't the game be designed with the backgrounds being one colour, power-ups another, and a prominent colour for enemies and projectiles?
When you destroy enemies, they may drop pickups. These only stay on screen for a good amount of time, but will eventually disappear.
You gain two types of points which can be used to unlock new weapons and upgrade them. You unlock a new weapon for each song you complete. There's all kinds of projectiles with different rates of fire, and strengths. You can equip four of these and even change the firing angle. You can choose which button fires them, or just set them to auto-fire. I didn't see a disadvantage of doing this, so I set them all to auto-fire.
As you equip these perks, the game gets easier and your score increases more. This system seems silly to me, because with this type of game, much of the replay value comes from returning to beat your previous scores. Since the game is giving you more powers, then it becomes guaranteed that you will beat your previous score when you return.
I did have fun with Symphony, because it is fun shooting things. The cluttered screen with the bland colour scheme doesn't really work for me, although the more I played, the more I got used to it. It's a similar type of game to Beat Hazard which I played recently, but essentially has the exact same flaws.