Fire Emblem: Awakening and Super Mario 3D Land are the must-plays for me. A lot of people think Kid Icarus: Uprising is the best game ever so I suggest giving it a spin too. I couldn't personally get into it because of the controls though.
Munster Hunter 3: Ultimate is amazing but if you have a Wii U I suggest you get it there instead because that version has online play.
Haven't beaten SMT IV yet so I won't comment but I did not like the first 20 hours. --- http://gamingforum.free-message-board.com/t1851-who-plays-sonic-still
"I intend to get Fire Emblem, OOT3D, and Link Between Worlds, but what about SMT or MH3?"
I have SMT IV, and the limited time I've played it (too many games), I've really enjoyed it. And I have Monster Hunter 3 Ultimate on WII U, and I like it, but I cannot comment on the 3DS version, sorry.
As for 'must-have' games. I cannot stand that term. If you don't like a certain type of game, you are not going to like a game in that genre, so nothing is 'must have'.
What types of games do you want to seek out, and that genres, past what you've already mentioned? --- To the mattresses. 3DS code: 2621-3902-1737, PSN: Justice_98405, Xbox Live: Justice98405
On past handheld systems, I really enjoyed RPGs. I've always played Pokemon, and FFTA was one of my favorite games for GBA. I like Shining Force. I liked Mario Kart DS, so I'll pick up MK7 as well. I;ve never liked shooters or fighting games on handhelds, I did have fun with Mario 64 on DS. I didn't have a ton of games for my DS, so I don't really know what 3D games really work well on handhelds. RPGs have always seemed to work pretty good with handhelds, so I guess that's should look for.
I really like Kid icarus uprising, I usually hate shooters too (unless they are futuristic shooters) but I love Kid Icarus... it reminds me of a third person unreal tournament/sin and punishment hybrid --- i7 3820@ 3.60GHz| 16GB Corsair Vengeance 1600MHz DDR3| Gigabyte GTX670 2GB OC| Intel 520 Series 120GB SSD| Antec EarthWatts 750W Green
Fire Emblem is a grid based rpg like Final Fantasy Tactics. That subgenre is usually referred to as "srpgs". Other srpgs on the system include Shin Megami Tensei: Devil Survivor Overclocked, and Tom Clancy's Ghost Recon Shadow Wars (I know, not the genre you'd expect from a Tom Clancy game.)
MH3U is my favorite and most frequently recommended game on the 3DS. I do recommend picking up a CPP if you're going to play though. It's not required (I played my first 160 hours without it) but it will make things, especially underwater, so much easier.
RF4 is an amazing game. It starts out a bit slow but once you get into the meat of the game it really picks up.
SMT IV is an awesome game and will easily eat up days at a time. It's got a high difficulty spike in the beginning but once you get into it and level up a bit things become easier. The DLC content includes a few maps where you can level up quickly and grind some serious maca. I suggest not over doing it or you'll over level and the game will get too easy.
FE:A is a great game and is highly recommended across the board.
Pokemon X/Y are, imo, pretty awesome worth a look if you're interested in this series.
M&L:DT definitely a great entry into this series. --- 3DS FC: 3781-0310-6225 PSN - AlbinoGerbil