Most beautiful 2D game ever

[Mnementh]

Of the games I played:

Monkey Island

Heroes of Might and Magic 3

Rayman Legends

Beneath a steel sky

Micro machines

Muramasa

And a bit of cheating, because these are actually 3D-engines rendering, although it is 2D-gameplay (this means lighting effects):

Trine

Octopath traveler