The Dink Network

Something that tries to be unique or different in any way, or add new elements to enhance the original game. (This is a good thing about PQ, for example - with the throwing stars and extra stats.)

Something that doesn't get tedious, doesn't have you grind for experience. Doesn't have you walk around a whole bunch of samey screens. Doesn't make you get stuck with convoluted character puzzles.

Something that has a lot of little secrets, easter eggs and hidden content or things like multiple endings.

Something that either has a strong story, or great humor, or doesn't take itself seriously, or becomes all surreal and meta on you (Moon Child)...