Ooh, that's a tough one... 1. Deus Ex 2. Gothic 2 + Night of the Raven 3. The Witcher 3 4. Fallout 2 / New Vegas 5. Baldur's Gate 2 Honorable mentions go to: KOTOR2, Dragon Age: Origins (the later games aren't worth mentioning), Mass Effect, Jade Empire, Neverwinter Nigts: Hordes of the Underdark. There are more, smaller known RPGs, which I've enjoyed immensely, but the top 5 if hard to beat for me.