I bought more than 100 DS games. It's my most favorite system of the Wii/DS gen. My DS passion still prevents me from bying a 3DS.
I agree with lots already mentioned, especially AoE: AoK, TWEWY and Radiant Historia. I haven't play AW: Days of Ruin, but Advance Wars: Dual Strike, which is excellent as well.
The DS has a huge library of underappreciated games imo (only by audiences, as many of them were appreciated by reviewers), such as:
- Soul Bubbles
- Alice in Wonderland
- Okamiden
- 999: Nine Hours, Nine Persons, Nine Doors
- Ghost Trick: Phantom Detective
- Hotel Dusk: Room 215
- Last Window: The Secret of Cape West
- The Wizard of Oz: Beyond The Yellow Brick Road
- Solatorobo: Red the Hunter
- Nostalgia
- Lufia: Curse of the Sinistrals
- Suikoden Tierkreis
- Glory of Heracles
- Etrian Odyssey II: Heroes of Lagaard
- Knights in the Nightmare
- Anno: Create a New World (similar to AoE this was a great handheld transition of a famous and successful PC franchise)
Dragon Quest games were not underappreciated on DS imo. Great games (the remakes and the new ones), good reviews, good to great sales.
I still wished SE had released Sigma Harmonics and Nintendo had released Soma Bringer in the west. Looked like great games (especially Sigma Harmonics) and had two of the best soundtracks of the gen imo. I still plan to play the Japanese version of SB with the English patch some day.
