If you've got a DS there are a lot of interesting turn based rpgs. Can't remember which I have off the top of my head but I've played a few.
Age of Wonders - http://store.steampowered.com/app/61500/ Turn-based RPG where you can have multiple heroes who gain experience and level up, as well as limited empire management as you can free/take over/befriend other towns and cities, upgrade them etc, and construct basic troops to supplement your heroes. Choose from humans, Elves, Haflings, Dwarves, Highmen, Azracs, Lizardmen, Frostlings, Dark Elves, Goblins, Orcs and Undead. Combat skills as well as spells can be learned, and you can boost heroes health, attack, defense and resistance too. Spells range from direct damage spells, defensive enchantments such as increasing your heroes defense, area-of-effect spells, even enchanting weapons and summoning magical entities and monsters to aid you. There's also world-map spells such as flight, teleportation, faster movement etc. I think there's a demo... http://aow.heavengames.com/links/aowresources.shtml#Demo There ya go. I adore this game. It has plenty of singe-player scenarios as well as the main story campaign, and each scenario can last a good long while depending on your style of play. I personally love to take over all the cities and turn by main hero into an unstoppable melee fighter. If a city has a wall with a single puny goblin defender, it's still totally safe from the biggest baddest Orc Warlord as long as they can't break down the walls. But a battering ram or catapult can sort that out.
