New area after Shy guy caves

Here's just an idea for a new area after shy guy caves

The under constuction pipeway will open, leading you through a short path that brings you to a toad guard. He says that he's lost and cannot find his way back to the castle. Yoo must then go to Peach, where she will write down directions for the guard, and then you can bring the guard the directions. This will open up his inventory.

Here's what the guard toad sells:
Castle Key-A key to the castle of the Mushroom Kingdom. It lets you open doors that are locked in there
Badges- More expensive but better stat boosting badges, because star piece drop rate is high in the shy guy caves, but the most expensive badge with star pieces is currently costing only 10.
Supplies-He carries a hoard of ultra shrooms, jammin jellies, and more.

Upon obtaining the key, you can then return to the castle to open up a few more rooms. I decided to put this in my suggestion, because Kimi said he wanted the castle to be bigger but ran out of time.
Kitchen-Here, you can talk to cooking toads. There's a recipe book that tells you all the food you've already cooked and their recipes. Talking to the toad in there every day will bring a randomly selected speech bubble in which he gives you a hint on how to make a certain item.
Back Door- This leads to a trench, in which you can use Jugem's cloud to reach the bottom and explore Goomba Gorge, the next large area.
Side Door-This brings you through a 1-3 map path, which, at the end, has Game Guy's Game house.

GAME GUY'S HOUSE:
Game Guy is a shy guy who just loves games and, in fact, has special 1-use clouds that bring you to any minigame buliding. He also does some other things.
-To activate Game Guy's Services, you'll need to bring him a complete set of Shy Guy Cards. This includes shy guy, underground shy guy, and elite guy. General guy isn't included as I'm aware there's only been 2 people who HAVE the card. Three that actually dropped, I think, but one was obtainable. Once you have exchanged the 3 cards for a special Game Card, you can access the lakitu clouds to ride back to the minigame houses.
-You can trade game tokens for special currency called Game Guy Gold, which you can redeem at his shop for extremely unique items. 100 WAM=1 Game guy gold, 2 DB=1, and 2 STS=1
-Game Shop: You can buy many things here. First of all, you can further exchange your shy guy cards for game guy gold. 2 shy guy cards=1, 1 UG shy guy=1, 2 elite guy=3, and 1 general guy=15
-Here's what you can redeem:
Bub-ulb seeds-Eating these gives you a special passive effect, but you can only know one passive ability at a time. You can choose to forget one, but then you have to buy another seed. Seeds cost 90 Game Guy Gold
Silver Card-Increases gain of STS coins by 1 if you win the game
Platinum Card-Increases gain of DB coins by 1 if you win the game
Badge pins-You can buy a mushroom, or flower badge pin for 50 Game Guy Gold. When paying another amount of gold depending on the tier of the badge, you can weld it to this pin and change the badge's type between mushroom and flower! It only works on mushroom and flower badges though, so you can't stack 3 attack speed ups, and other crazy combinations. This is pretty useful for getting block rush but still wanting good defense from a flower badge, and you can make all sorts of other combinations with it.