Whenever people bring up the "games as art" discussion, I am surprised that people don't bring up Okami enough. It is a legitimately beautiful game.
The art design is one of the most unique designs in gaming. The Japanese-style watercolour theme for the game makes everything look like a painting come to life. And the music is simply breathtaking. Every song captures the mood that's trying to be set perfectly.
In terms of gameplay, some have referred to this as a Zelda clone. And maybe deep in its core, it is, but really, is that a bad thing? The Zelda games are so beloved because they have a tried-and-true gameplay system. What's wrong with someone else giving it a shot? Plus, there's not as much focus on dungeon-crawling as there is in most Zelda games. You actually spend more of your time in the overworld than the dungeons.
The characters are all unique and well-developed. One I want to mention is a character that doesn't even impact the plot. Her name is Camellia, who travels through the world with her younger sister, Camille. Camille believes in the gods, but Camellia doesn't, and the more you interact with them, and the more you do for them, the more Camellia starts to believe. It speaks about both the character as she develops, and about the game itself, giving you the chance to change someone's perspective on life.
It also ties in with the story and its themes. As the goddess of the sun, reincarnated as a wolf, you have to travel through the lands and banish the darkness polluting it, while also restoring the people's faith in the gods. There's a rather heavy nature vs. technology theme, but also an interesting story about people learning to believe in the gods again, while also trying to not rely on them too much.
Okami is a game that deserves a lot more credit than it gets, and it deserves to win here.