The Portal games are fun puzzle FPS platformers with a great story, though there’s a good chance you’ve already played those and didn’t consider them platformers.

I also want to second Psychonauts. I haven’t played #2 yet but the first game had a unique and interesting story with fun gameplay.

I’ve heard A Short Hike is a relaxing game. More about exploration than meeting game objectives but could be a nice break when you’re stressed.