Games I've Played That Don't Exist
All of the ones that I can currently remember occurred during the ten E3's I went to between 1997 and 2006. Sometimes at E3, you play something that just never materializes on store shelves. Shockingly, there's even a few situations where it's something that was promising, so it's disappointing that the game never made it. For example, I really enjoyed the StarCraft Ghost multiplayer. Battlefield 2142 ended up taking their idea for a moving aerial base.