Mother-fraking Luigi's gorram Purple fething Coins! (ie Luigi's Purple Coins from Super Mario Galaxy) I did have an epic feeling of accomplishment when I did finish though. I went into that galaxy with 139 extra lives and came back, star in hand, with none.
Another thing was Horizon from Mass Effect 2 on Insane as an Infiltrator. Two days worth of focused gaming effort were to no avail, I ended up turning the difficulty down for that. I eventually beat Insane with a Soldier, much easier (not quite as fun).
Oh yeah, Mile High Club from CoD4 on Veteran. I actually beat it but that was on my brother's profile. Since I've made this new gamertag I tried to beat it again but couldn't. It really annoyed me when the timer ran out during the firing animation that would have killed the last terrorist.
Another thing was Horizon from Mass Effect 2 on Insane as an Infiltrator. Two days worth of focused gaming effort were to no avail, I ended up turning the difficulty down for that. I eventually beat Insane with a Soldier, much easier (not quite as fun).
Oh yeah, Mile High Club from CoD4 on Veteran. I actually beat it but that was on my brother's profile. Since I've made this new gamertag I tried to beat it again but couldn't. It really annoyed me when the timer ran out during the firing animation that would have killed the last terrorist.