Flower?
Yeah kinda? There isn't much gameplay there but I can't think of anything else that similar.
for honor
That's a great example. It's hard to remember that it really is like nothing else out there, even though its plot and theme are so generic.
A lot of good ones have been mentioned already.
One that probably doesn't count. Dark Cloud. I can't think of any games like it. It's basically an RPG where you collect parts and you build towns using them.
It doesn't really do anything brand new, but it combines a few things together in a cool way that I can't think of any others.
Yeah that'd be a variant. Takes an existing gameplay premise and then adds/removes a mechanic that significantly changes things. Still though they are really interesting in their own right.
FPS with time slowmo
Sidescroller action shooter with time manipulation.
2D platformer where you control the world instead of the player.
Probably Mario Galaxy with its gravity mechanic. Made its platforminn much more interesting.
Yup a variant as well. The jumping was so cool in that game.