Dragon Age: Origins
An instant BioWare classic, Dragon Age: Origins took what makes tactical fantasy games great and perfected the formula, providing a deep and intense party-based combat system that played out in real time and could be paused to grant the player some tactical advantage. On top of all that, the game featured an epic and thrilling fantasy story that was complemented by great attention to detail, both visually and otherwise.
The way your story unfolds depends on what kind of character you create and develop, how you interact with the people and world around, you and what paths you choose to follow, allowing you to tailor your own unique story experience. This lends Dragon Age: Origins an incredible sense of replayablity since no two playthroughs feel alike, which is what makes it the timeless gem fans claim it to be.