One of the best roguelikes of any category and classification ever. It's not about the graphics, or the story, or a coherent packaging (which many roguelikes struggle with) -- which are all amazing. It's about the core gameplay loop which is immensely satisfying. Each tactical decision, each move, is important. You have an infinite amount of options on what you want to tackle and how. Before you even reach that level, the game has hundreds of hours of exploration, lots of worldbuilding, lots of experimenting. Is it hard? Yes, and that's the best part. It's hard in a fair and fun way.

Path of Exile but single player

My favourite old school turn based roguelike, Never gets old for me, I always come back.