Flintlock
Pro Adventurer
I listed my favourite DS games in that thread Octo made a while ago, and they're all playable on the 3DS, so those are my recommendations.
If I had to pick a couple out, I'd say Broken Sword and FFTA2. Obviously Chrono Trigger is amazing as well, but you can get basically the same experience by playing it on a SNES emulator, while those two games are really at their best (or exclusive, in the case of FFTA2) on the DS. I dunno if you're interested in point-and-click games though.
- Broken Sword: The Shadow of the Templars
- Chrono Trigger
- Final Fantasy IV
- Final Fantasy Tactics A2
- Mario Kart DS
- New Super Mario Bros.
- Phoenix Wright: Ace Attorney
- Pokémon SoulSilver/HeartGold
- Rhythm Heaven
- WarioWare: Touched!
If I had to pick a couple out, I'd say Broken Sword and FFTA2. Obviously Chrono Trigger is amazing as well, but you can get basically the same experience by playing it on a SNES emulator, while those two games are really at their best (or exclusive, in the case of FFTA2) on the DS. I dunno if you're interested in point-and-click games though.