A game that plays almost exactly like Amplitude, but much more focused on techno-style music. Fun rhythm game!
I feel in many ways that Amplitude and Frequency play almost exactly the same way, so I'll direct you to my Amplitude review and discuss their differences. Frequency's main difference is that it is much more focused on what could loosely be described as techno. This includes everything from genres such as "big beats", house, trance, and other genres. There is a bit of hip-hop to be found, but much less rock than is found in Amplitude.
Other than that, there are a couple of power-ups found in Amplitude missing here, but they don't affect gameplay much. Additionally, the backgrounds are more fully 3D in Amplitude, but you'd scarcely notice while playing it. Other than the music, things feel almost exactly the same.
Which brings me to the same problems I had with Amplitude. While the gameplay can be very challenging and enjoyable, I had only heard of about 4 of the 20 plus artists in the game. I was familiar with only one song! This took away a lot of the fun of making the songs play, because I didn't know what I was playing. There were no GH style moments of, "Oh man, I'm really playing Iron Man!" I just felt like I was making random drum loops and keyboards kick in at many points in the game.
If you loved Amplitude and like techno, this is a must own for you. If you hate techno, I'd avoid this one. I really enjoyed this game, but it is really hard for me to choose this over my beloved Guitar Hero when I feel like a music game. Solid title, though.