Not sure if these are underrated animes because "hype" might be a function based on when and who you are around. (Like I know pretty little K-pop music, though I pretty sure it is world-wide popular now)
.hack//SIGN
The first "get stuck in a video game" story that I know of.
Builds more on character relationship and drama & trauma, rather than completing video game goals: battles, leveling up, dungeons, etc. (little to none). Also, the music is great.
Tsuritama
Colorful weird characters and fishing. It's a fun time!

Hello Kitty animated series
Short simple stories for children for each episode, which is sometimes it is good to watch amongst all the dark and complex stuff happening in other stories or real life. Happy endings and lack of cliffhangers.

NOT linked: "https://en.wikipedia.org/wiki/Listof_Hello_Kitty_animated_series"_