So, I recently found my 3DS which I had bought at launch and then left at my parents house for years. The only games I had initially for it were Ocarina and Mario Kart. I always hear about how strong the 3DS/DS library has become over the years. What are the must-plays or just generally fun games that I should pick up for it now? I now have Mario 3D Land and the first Professor Layton and am enjoying the hell out of them.

Etrian odyssey 4, a fantastic dungeoncrawler that is probably the best first step into the series. There's a demo to try out beforehand if you're not sure.

Rythm Heaven Megamix, A collection of a ton of the minigames from old games in the series, sprinkled with some new ones. Great, charming and simple Rythm-game.

The Fire Emblem games are overall pretty good.

Pokemon Sun/Moon is also really good.

Phoenix wright games, start with the trilogy-collection.

There's alot more, but these are the standouts for me.

If your into RPGs then dive down the rabbit hole and go nuts. Quick shout out to Solatorobo: Red the Hunter, Chrono Trigger, The Dark Spire and The World Ends With You on the DS.

There's a lot of smaller eShop games as well I'd recommend checking out such as Attack of the Friday Monsters! A Tokyo Tale, Nintendo Pocket Football Club and Woah Dave!.

Then again perhaps you want some of the bigger, heavy hitters such as Luigi's Mansion: Dark Moon, Pokémon Omega Ruby/Alpha Sapphire, Monster Hunter Generations, Yo-kai Watch, Kid Icarus: Uprising or Animal Crossing: New Leaf.

There's also The Legend of Zelda: Majora's Mask, Puzzle & Dragons Z + Puzzle & Dragons: Super Mario Bros. Edition, Steel Diver, Tom Clancy's Ghost Recon: Shadow Wars (XCOM on 3DS) and Star Fox 64 3D kicking around as well.

I've also only recently begun to dig into the catalog for this console. Been having a great time so far. Here are a couple of suggestions from what I've seen up to this point.

Shin Megami Tensei 4. There's a slight difficulty bump with the first boss, but the difficulty curve is totally reasonable after that part. Not even just by the franchise's standards, either; legitimately reasonable. Out of the mainline SMT games, this is the easiest to get into I've ever played. Good puzzle-ish combat where you prey on enemy weaknesses to gain additional turns each round. Demon negotiations are as baffling as ever (I've had a bit of a love/hate relationship with this system for well over a decade), but they provide some ways to make it easier. Fusing is as good as it's ever been; they even provide a bit of a path to follow with a list of "special" fusions that require more than 2 demons if you find yourself overwhelmed by choice. No random encounters, if that sort of thing bothers you.

The Legend of Zelda: A Link Between Worlds. A Zelda game is good? Whaaat? This may be my favorite Zelda period. The new mechanic of going 2D is used quite well. They also make almost every tool in the game available very early on, which is nice. At first you rent them (rental period is over upon death, but honestly who is dying in a Zelda game? Get some heart pieces, fill a bottle or two with Fairies, you're good don't worry bout it), but you get the option to buy them outright pretty quickly. There's a set of collectibles, but the rewards from getting them are fairly substantial. This game swallowed me whole for about a week and a half. I did everything (as far as I know), but I'm excited for the point some years from now where I can come back to this game after I've forgotten enough about it.

My DS Lite eventually became almost solely a Picross machine. I never finished Radiant Historia, but I thought it was pretty good. The Dragon Quest remakes were all excellent as well. The last bastion of JRPG goodness.

Too much to recommend D:

Well, if you have Ocarina, get Majora, which has become my favorite Zelda of all time.

The two Kirby games (Triple Deluxe and Robobot) are surprisingly great, with Triple Deluxe being my favorite on the system for a while.

Fire Emblem Awakening is awesome. The game that got me into strategy RPGs.

The New Super Mario Bros games are a good dose of classic 2D Mario fun. Only played the Wii one myself but eagerly looking forward to playing the copy of the first on the DS I just got from my cousin. You've also got Super Mario 64 DS if you can deal with the controls. It varies from person to person, but the game itself holds up well all these years later (played it on my Wii) and there's extra content including 30 new stars.

Mega Man Legacy Collection is good if you're into older, hard 2D platformers, as is Castlevania off the VC.

Pokemon is Pokemon. You already know if you'll like it or not, and there's plenty to choose from on both. SoulSilver/HeartGold and Sun/Moon seem to be the standouts.

Also off the eShop, you can grab Shantae and the Pirate's Curse for a great mix of Zelda/Metroid style progression and platforming. Awesome game that I fell in love with.

If you're into Sonic, you have a lot to choose from on the DS. Classic Collection and Rush are my personal picks.

A Link Between Worlds was a joy for me from start to finish, so that's always my number one recommendation.

Rhythm Paradise Megamix and Picross 3D Round 2 from last year are also very very good.

Picross 3d Round 2

Pushmo

Rhythm Heaven Megamix

Phoenix Wright Trilogy

Zelda

Pokeman

Animal Crossing

Mario

Those are my favorite anyway.

My favorites have already been said, but I'll go ahead and reiterate: The Fire Emblem games are great if you like turn based strategy, Pokemon Sun/Moon are great pokemon games that actually try to mix up the formula a bit, and there's the Monster Hunter games. The 3DS version of Animal Crossing is one of my favorites in that series so if you're into those games it's a good version to pick up. If you're into Shin Megami Tensei games I'd pick up Apocalypse as well.

WarioWare Touched for the original DS is one of my all time favourites

Advanced Wars Dual Strike was awesome too, I think there was a second DS advanced wars but I remember it being weirdly dark

If you end up enjoying Phoenix Wright then grab a copy of Ghost Trick. It's written by the same guy and stars you as Sissel the ghost cop stopping murders around the clock

Professor Layton vs. Pheonix Wright or any games in eitherseries. The Zero Escape series. The threeDSCastlevania games are all worth playing.

Some weirder eShop only stuff that is worth checking out:

Attack of the Friday Monsters

Crimson Shroud

Gunman Clive

Tappingo

BOXBOY!

I really like the most of the Dragon Quest remakes (especially V) and DQ IX

Professor Layton series

Pheonix Wright

Etrian Odyssey series (especially IV is a good starting point, although Untold 2 is pretty good too)

7th Dragon III (another dungeon crawler similar to Etrian but arguably better)

Pokemon (Black/White 1 & 2 for content, Sun and Moon for shiniest presentation)

Shin Megami Tensei IV and SMT IV: Apocalypse

The World End With You

999 and Virtue's Last Reward are both in my top 5 favorite games of all time.

I've seen a lot of people suggest Phoenix Wright and The World Ends with You, but both of those are available on iPhone, and I'd recommend playing them there. I'm actually replaying TWEWY on iPhone right now and I like it better there than on the DS.

Persona Q, but only if you're familiar with/attached to both 3's and 4's characters

Pokemon Black/White 1 and 2

Link Between Worlds

Picross 3D Round 2

SHINOBI(3ds) is THE BEST game nobody played. By far one of my favorite 2d games on the system. Dont let the bad graphics fool you.

Crimson shroud on the estore is also a really cool, short but hardcore d&d tabletop inspired jrpg. If that sounds like something you'd enjoy I'd recommend checking it out.

If you haven't played Shovel Knight then I would say it's the best platform for it. It lacks co-op but it adds streetpass fights, still that is all extra stuff that wasn't there from the start. The Treasure Trove package is damn good.

999, VLR and ZDT is a good trio of stuff if you enjoy mysteries and twists.