By the power of truth, I, while living, have conquered the universe.
Posted by: Lillehammer
I was going to say Portal and the Arkham series, then I remembered that both sequels were inferior to their predecessors. I guess Borderlands?
I can't speak for the Arkham series, but I much preferred Portal 2 to the first game. The story was better with more interesting characters who got a great deal of development - Wheatley, Cave Johnson and GLaDOS/Caroline were pulled off beautifully. The gameplay had more variety with the various gels, and there were some truly memorable moments, especially the ending.
Portal 2 is how a sequel should be made IMO.