Today, a remake of the original Pokemon Mystery Dungeon game was announced, called Pokemon Mystery Dungeon: Rescue Team DX.
This got me thinking about how I've also seen the "DX" title in lots of other remade or remastered games, including Pokken Tournament DX, Tetris DX, and Link's Awakening DX, but have no idea what the acronym means and have never seen it used for any media other than games.
So, my question: what does DX actually stand for, and how/when did it become a term meant to indicate remade or remastered video games? Googling only came up with "Deus Ex" or "Diagnosis" as possible acronyms, and neither of those make much sense.