It's osu!... apparently.
Lately I've been playing this game that's simply known as "osu!". It's a rhythm game that only uses the mouse. You click on circles and follow "slides" to the beat of whatever music is playing. It's a decent game if you're into rhythm games, but it's good for another reason which I'll get into a bit later.
The music and rhythm charts are supplied by the community, and since it has a Japanese sounding name, it attracts similar music. It's not all bad though, it's more along the lines of music you'd hear in Dance Dance Revolution instead of the high pitched anime theme songs. If you're into J-pop then more power to you.
The circles are conveniently numbered so you don't get confused on the order.
The game play consists of 3 different uh.... things. Circles that pop up that you need to click as soon as the ring surrounding it hits the edge (as seen above), two circles connected with a slider, which work the same say as the circles except you have to follow the slider to the next circle after clicking the first one, and a giant turntable looking thing you have to spin around a number of times before the time runs out. It's pretty simple but it gets fairly hard to keep up at higher difficulties.
So what's the real reason I'm talking about this game? Well, it's the perfect "fun" way to train your mouse control. Weather you play RTS, FPS, or just click in WoW (lolololol) you need to be able to move your mouse quickly and accurately, and you don't always get the high APM required situations needed to repeatedly practice. If you're looking for a different way to increase your mouse skills, try this out. Play until you're good enough to do 4-5 star songs and then tell me it isn't easier next time you go to split your Marines.
Give it a shot, let me know if it's fun. Or don't, that's okay too.