Djinn
and Tonic
Honestly I would want to say neither, there are a lot of games that I enjoy that are not light hearted but they cannot be described as dark either. I do enjoy a bit more realism to a game but that should not always translate to gritty, horrible human suffering everywhere you go misery in a dank and old setting with torn up buildings everywhere. Nor do I care for cartoon fun time where everything if perfectly G rated happiness. We have games like Kirby for that so I don't believe it is needed in a Zelda game either. Many adventure games can have an interesting balance of both and have lighter spots and darker spots but over a well balanced atmosphere. There are several Final Fantasy games that can fit into this mold easily enough. Yea there are some light hearted scenes, and yea occasionally people die and there is often a dark themed temple or two. But that is generally it as far as specializing in one area alone.