Psychonauts 1
SUCH a cool concept and really well executed (especially for 2005). Basically you use psychic powers to travel into someones mind, and see a visualisation of their main issues/fears/dillusions/memories/etc and help them sort put their baggage or come to terms to stuff. Each brain looks and behaves completely different, and is SOO well designed. The character and level designs are so fucking good. It's a really abstract game that's hard to describe. you just gotta play it.
Psychonauts 2
Continuation of the story, focusing on six great psychics and going over what happened to them 20 years ago when they were at their prime. They pushed their brains and mental powers too far, making them all vulnerable, but when one of them went off to help fight a war, it all started cming apart. There is also yaoi. Its such a beautiful game. You can really tell how much time and effort went into the design of every single character, level and plotline.
Deltarune
I have tried so hard many times to put into words what deltarune is and have never been able to. It's so much more than how I would ever explain it.