The subject line (and, indeed, entire thread) is a blatant rip-off from one I've been reading recently on NTSC-UK, but is one of the best ideas I've ever seen. The idea is to post with (preferably fairly recent) elements in games you've been playing that took you ages to work out.
For instance, I unlocked nearly all of MotoGP and had been playing it for months before I realised you could powerslide by double-tapping the accelerator (or releasing it and going straight back on to the juice, more accurately), which made it far easier to get round bends.
A lame example, but you get the idea.