There are a few greats that are my benchmarks. The ones that rise to the forefront, however, are Fallout, Baldur's Gate 2, Planescape: Torment, Half Life, and System Shock 2. If I had to pick one as that amazing unreachable game, I would pick Planescape: Torment. While some games surpass it (Baldur's Gate 2 is a better true-blue RPG), the dialogue, characters, creativeness and world just skyrocket it to a work of genius.