Mine has to be Dragon Quest: Rocket Slime, a DS spin off of the Dragon Quest series that sees you playing as a slime operating a tank and rescuing the people from your town. You run around the overworld, collecting items to use as ammunition and saving money to upgrade your tank. The art and music are just as great as you’d expect from the Dragon Quest series. It made fantastic use of the DS’s dual screens. It’s also written for a younger audience, so a lot of it is just really silly and fun! Try it out for sure, I’m so sad there’s no sequel :(
Invisible, Inc. Klei has created other great games so probably Invisible is not that unknown, but it seems that this game is forgotten both by gamers and developers. The subreddit was dead (when reddit was relevant), nobody streams it, and Klei continued to add content or sequels to other games like Don’t Starve but nothing to Invisible.
Turn-based tactical stealth was a really cool mix, and it’s surprising nobody else has done something like that.