Pick a song. Blow crap up. Have an absolute blast!
First step, pick a song. The game starts you with many great and playable songs, and supports many different sound formats, predominately MP3s and updates are providing more, so you'll rarely run out of music from your own library to play to. Second step, pick up and play. There are 2 game modes: normal and survival, and the choice of 4 difficulties which affect how intense your game is going to be, how many enemies will spawn, and how flashy the graphics are going to get...and trust me, the game gets flashy with its gorgeous but simple graphics.
Beat Hazard takes your song and uses the many changes in tempo and rhythm to determine what enemies will spawn, how many, how intense gun fire will be and many other aspects. If the song is slower, you'll have to rely on ducking and weaving through dangers until the song picks up, as your weapons will lack major power, but thankfully the game controls really well, and I never ran into an object unless it was my fault. I can't express how cool it was to dodge and shoot to my favorite songs, and the game integrated them flawlessly.
As you play you collect multipliers for your score and powerups which affect the volume of the song and the power of your weapon, both of which ultimately make you more of a powerhouse. Things may start slow, but as the pace picks up and gets in full speed, this game has the screen covered with bullets, enemies and graphics that don't let up. Sometimes the screen gets so flashy and ridiculous that it may seem distracting, but I've never been so annoyed that I wasn't having less than a ton of fun. Boss fights especially leave you feeling all kinds of "WTF is happening on my screen?!?!"
To add some extra mileage, the game has a leaderboard for different ranks lengths of songs you play, a standard yet lengthy share of practical achievements, and most addictive of all extras, a sort of in-game leveling system that has you power-up as you accumulate points. Each level usually gives you a reward like starting you with extra lives, bombs, multipliers and such, so you're able to keep amping up your intensity as you progress. While the overall package might seem simple, its also a pretty good value, as you can find it on Steam for $10 or less if there are deals running.
If you love shooters like Geometry Wars and you'd love an opportunity to blast away to the most epic music you can think of, or have some casual fun to some casual music, this game is a great time filler that can get really addictive. It may not put out a 30+ hour story, but in short to moderate spurts it can provide you with some intense and truly gratifying action.