KRAZYRAIN - International version website.
I'm not sure where else to post this, so I'll post it here.
Krazy Rain is a free online Korean rhythm game much like DJMAX, EZ2DJ/ON, o2jam etc. that has a 5key and 7key mode with a score multiplier similar to the fever system of DJMAX. It's activated with the left shift key and stacks up by 2s. I think it takes away a big chunk of health, and also ends if you miss one note so be careful.
Interestingly, there is a mode where you can switch between 5key and 7key modes in the middle of a song, but I haven't tried it yet.
This game has an international version, so you can just sign up for free, download the client, and play.
The game has quite the graphical presentation, but currently only has few songs by a small amount of composers and remixers.
It features a single player and a one-on-one versus mode, global servers with world score ranking, friend list etc.
It's free, so give it a shot. Right now there is a
Kia Soul promotion event, so expect some not-so-subtle advertising.
Have fun!