Green Day: Rock Band

Lefty Mode can either be triggered at the difficulty selection screen after picking a song or in the pause menu during a song. Obviously, make sure Lefty Mode is on before the song even starts in order for you to get this achievement.

You can do this on any song, and there is no difficulty requirement. So you can just break out your guitar or drum set, pick your favorite song on Easy, flip on Lefty Mode and just play. Hitting 50% of the notes isn't terribly hard at all.

Of course, if you're naturally left-handed then this achievement will most likely pop on the first song you play!

This can be done in Career or Quickplay.

The way I got this is not any way better than any other method, but I think it is more challenging and fun. Mind you this method only works for Guitar or Bass.

I picked a moderately slow song, Last Night on Earth, but the song choice doesn't necessarily mater, as long as you are capable of playing it. Once I put the Lefty Mode on, get ready, I laid upside down on my bed and played the song that way.

The charting is exactly the same as if it were standard and not lefty. The only catch is that the notes fly upwards instead of downwards. The great part about this method is skipping the boring aspect of playing on a lower difficulty than you are used to. The only trouble anyone could have with this is the adaption to the flow of the notes.

I hope this method works for some of you and gets you the achievement. Maybe some of you will play like this regardless as a challenge to yourself when playing the same songs over and over again for the other achievements gets dull.

You can also just set up a mirror behind you and play into the mirror. Although this achievement isn't that hard so that might be to much work.

The easiest method I found for this achv:

Song: Wake Me Up When September Ends
Instrument: Bass
Difficulty: Easy

This song is great because about 40% of the song doesn't even have a Bass line.