I'm asking this question because,
1. I haven't been on BYOND in quite some time.
2. A friend of mine made a jab about BYOND having no beautiful games. I'd like to hope that just isn't true.
3. Just having some raw data on what graphics are enjoyed and what aren't is good data; it sort of let's us all know what key features are commonly found aesthetic, and which aren't. Games are designed with the commonhood in mind, and the more known about the commonhood the better.
Commonhood.
Of course, to go with that third bullet, I highly doubt 80 people are going to reply with their favorite games, and I doubt there will be a lot of common 'submissions' that point in a direction of what looks good. More likely, anywhere between 0 - 15 people will reply, and only 5 will submit games, and they'll all be different, and so it would be much harder to answer any sort of statistical questions. But at least my first two bullet points would be answered.
Cliffnotes:
Are there any beautiful games
What's your favorite game
My personal Criteria for Beautiful Games
1. The first, and obvious, is the actual quality of the individual icons. A super well drawn grass is generally better than the three-dots-and-flood-abuse grass we could make in 12 seconds.
2. The second, and what can completely nullify the first one, is ..how should I say this..matching. I'm going to call it the 'icon clock theory,' or 'icon society.' If one icon looks like it was finger painted by Stephen Hawking, then they all should. The very agreement in all of their parts makes the whole look much better. They all work together for the greater good, like the gears in a clock, or people in society. So ..yea. Icon Clock.
An example would be FF1, which I enjoyed (graphically)(I'm probably just being hipster tho)
much more than several byond games I've played.
(http://wiimedia.ign.com/wii/image/article/103/1031300/ final-fantasy-20091005090019998.jpg for reference)
3. Color tones
This is simple; the tones set the mood. I prefer some tones over others.
4. Tile-less
This has been mentioned in much of the main pixel art literature out there ( not that there's much of that at all); mapping is generally considered better if you can icon in a way that makes the player forget that everything from 16 tiles on your kitchen floor to the great billions of grains of sand in the Sahara is being represented by 16 tiles on your kitchen floor.
Sometimes tiles are ok, but something about Byond games have made me aware of a whole new sort of overly-tiled games.
Any style is fine, as long as it is consistent. I personally prefer bright colors and implied detail, but i'm branching out.