Good news, everyone! Revit 2018.1 update is now available for download from the Autodesk Account portal. It comes with some cool new features (see this article at Autodesk blogs for the full info), including enhancements to Dynamo Player. Now it finally supports changing input values directly through the Player UI, which is super handy:

As you can see, there may be plenty of inputs that could be changed without even launching Dynamo. But note that there are still some limitations:

• Code blocks as input strings are not  supported – if you prefer to write text inputs in code block, using quotes, you’ll need to rebuild these Dynamo graphs (swap Code Blocks with Strings) to use with Player;
• Custom nodes as inputs are not supported – they are not shown in the Player UI;
• Frozen nodes will be shown as changeable inputs, while they’re not used in the script logic.

Anyway, this is a cool update, and I’m sure that these subtle issues would be fixed in the near future. And by the way, here is the quote from Dynamo community addressing these issues:

We will look into the frozen node and address them in the future.
For the Code Blocks it’s a little more tricky but doable if there is a strong request from the community.
For the custom nodes it would be really nice indeed to have that.
The way I see this as a possibility in the future : a third party will create the custom node on Dynamo and then will have to create the node UI representation in Dynamo Player ( using some Dynamo Player API which doesn’t exist yet ). So the third party will have control over the DB level of the node and also over node UI representation in Dynamo Player.
Good news is that things are designed internally to make this possible in the future.
However , since this still requires a significant development effort we need to have a strong request from the community so that decision factors prioritize this accordingly. So please tweet about it on every occasion !