If you are reading this, i assume you are as chronically online as i am, so i think it's safe to say that Celeste needs no introduction. From frame one the game already gives you a tight control scheme to play with, even before the upgrades you get in the game. The devs really did a great job making Madeline such a fun little gremlin to move around the screen.
What makes Celeste special to me personally has got to be the music. I have been listening to the game's soundtrack since way before i ever played the actual game, so seeing the music naturally develops as the story goes is such a treat for me.
All in all, i think Celeste is such a good game all around. All the sights and sounds all complement each other and it all makes for a pretty neat little package.