Captain Toad's Treasure Tracker is a fun little side game that isn't too long or particularly difficult, but high on cuteness.
Gameplay:
This game features both Toad and Toadette solving puzzles in mostly square-shaped levels, finding treasure and stars to advance the game. Generally this involves moving ramps around, dodging or disposing of goombas and other enemies, and changing camera angles to find all the hidden secrets. It's not a very difficult game, and even getting a game over doesn't impede your progress hardly at all.
There are 3 chapters, but I think 2 would have been sufficient. By the time you're nearing the end of the third chapter (all chapters have around 20 levels that each take about 5 minutes to play through) you're used to all the gimmicks and ideas the game has to offer and will be ready for it to be over. However, even up into the third chapter the game surprised me with a couple unique and fun levels that I wasn't expecting, including a music-themed level where you have to time everything perfectly. However, I still think they could have taken out many of the "fluff" levels and just had the most creative ones in 2 chapters and this would be a better, more compact game. Maybe Nintendo wanted 3 chapters to justify a $40 price tag here, but even with 3 fully fleshed out and better developed worlds, this game wouldn't be worth $40.
However, it does have some high points and the cuteness factor is real in this one. Toad and Toadette are adorable and walking around solving little puzzles consistently left me with a big grin on my face. Some of the hidden objects are downright difficult to find, and when you do find some of them it feels very rewarding. Others are just laying around haphazardly or appear when you kill enemies, but hey I'll take what I can get. One issue I do have is that on the Wii U, which this game was designed for, the controls work well, but I replayed this game on the Switch and the controls for moving cogs and clicking on switches is downright bad. The controls take up the entire screen so you can't see anything else that's going on, which frequently leads to unnecessary deaths for poor Toad.
Story:
Who knows. Who cares. You're Toad and there's a bird stealing your treasure. That a-hole has to go down.
Music:
Unfortunately I think Nintendo went with the nostalgia factor too much and used a bunch of music from previous Mario games that is barely changed at all. There are a couple songs worth listening to, but overall this soundtrack is not inspired.
Toad's Treasure Tracker started as an extra in a Mario game, and turning it into it's own game was worthwhile. It's fun, clever, and cute. However, this game is not worth $40 and I would only recommend picking it up when it goes on sale in like 5 years since Nintendo never lowers their game prices.