Code Studio from Code.org has many coding options including complete 20 hour computer science curriculum. For primary grades, you should start with Course 1 for pre/early readers and Course 2 for readers.
I highly recommend the CS Fundamentals Unplugged (which are included as unplugged lessons in Course 1 and Course 2) for introducing coding concepts to students and helping teachers to learn the vocabulary of computer science. These unplugged activities also give students hands-on learning that is so valuable in the primary grades.
Advantages to Code Studio
Play Lab Ideas:
The main disadvantage to Code Studio is that it is mostly problem-solving and puzzle levels. There is not much in the way of creativity and creation of open-ended coding projects.
There are some additional themes for Course 2 Play Lab as well as a Disney Infinity Character Play Lab.