9. Killzone 2's Too-Good-To-Be-True Reveal Trailer (E3 2005)
The sad truth is that gameplay footage shown off at E3 isn't always 100% representative of the end product - few will forget the disappointing graphical downgrades Watch Dogs received between its mesmerising E3 premiere and eventual release.
But at least developers will generally show off an actual, working build of the game, especially these days where scrutiny on "bullshots" and cooked-up "gameplay" is more intense than ever before.
Sony certainly learned their lesson back in 2005, when they dropped an insanely impressive trailer for Killzone 2 on the PS3.
At face value, it was an incredibly persuasive advert for the PS3's technical capabilities, seamlessly melding high-quality cinematics with tight FPS gunplay.
However, members of the press speculated on the veracity of the alleged gameplay video in the days following the conference, causing Sony to admit that it was in fact a "target render."
Though the final game was certainly a landmark title for the PS3, it never get close to the fluidity and detail of that initial trailer.
In recent years it was revealed that the video was actually initially made for internal use only at Guerrilla Games, before Sony grabbed it and put it in their conference. Yikes.