During my first (of three) playthrough of Mass Effect 1, I encountered a strange... bug? that has since prevented me from attaining a couple of achievements. To elaborate: during the final sequence - ...
I completed my first playthrough without reaching level 50 or 60 (there are achievements for attaining both of those levels).
I've run out of grenades against the colonists and cannot figure out how to melee attack. I was instructed to use non-lethal force (either grenades with the Anti-Thorian Gas mod or melee attack).
I loved the original Mass Effect. I've played through it multiple times: I have one character at level 60 (canonical, with which I played through thrice), another at level 50-something (female ...