Originally Posted by yuyanami
Flip You. Flip You For Real 20
Kill 50 enemies total using the Melee Attack.
Run up close to an enemy and press R2 to do a melee attack. Kill 50 for this achievement. In the later stages, enemies with red health bars will not die from one melee attack so be careful. Enemies with blue life bars will still be taken out with one attack. It's hard but possible (unadvisable) to do them on heavy armored guards from behind but there's no point.
I presume your writing this guide for the 360 as this site is mainly for the xbox 360 and it's achievement system. I think you got a bit confused with the PS3 controller there if i'm not mistaken. I'm having a wild guess here but the melee button on the 360 would be "RB"?
Nice guide though nonetheless.