It's hard for me to pinpoint any singular games as most creative since a lot of games do pretty creative stuff within different genres. I liked the creative 4th wall breaking stuff in Metal Gear Solid for example, such as how it used the controllers vibration to make it seem like Psycho Mantis moved your controller with his mind. That blew my mind as a kid.

I've also been playing a lot of splatoon 2 lately, and I think it's a pretty creative way of blending the more cartoony and colorful aesthetic of Nintendo and mix it with online shooters. I feel like it's one of the most creative games of that genre despite its shortcomings.

There is also a lot of creativity in the indie side of things that I don't have much experience in. I feel like undertale would be on this list for me. Probably hotline Miami too based on watching other people play.