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 :(
Man, I haven’t played it in decades, and I can still remember the soundtrack. Great game! I can count on one hand the number of fighting games that I’ve bothered to learn all the moves for, and OMF might have been the first. Just had the shareware version for years, then happened upon a licensed copy in an old box of 3.5" disks. Good times.