A key language aspect is await/async semantics for asking users questions like "which piece would you like to play". While using async is not unique, the document memory model is transactional such that the async messages can be rewound. This allows a single incoming message to translate into exactly one data differential which means now the entire experience can be done in spite of machine failure.

When I was writing games with JavaScript await/async, it was a giant PITA. First, either the transactional boundary was too large and I had to replay an entire round while testing, or I had a lot of bugs. And bugs were exceptionally common which require building a lot of framework.

The database is basically how to productively work within the document, so the primary collection is a table which has basic integrated SQL. I haven't had a need for joins yet, but I plan on them in the future.