I wrote a spreadsheet based rules engine at Honeywell in around 2003 which enabled the business to maintain the business rules for all sales contracts that ran through the automation and control systems division. This gave them the ability to define forms, subsets of forms (legal or otherwise), notifications and approvals. I had its own natural language based expression language which the super users and business analysts could easily understand.

The spreadsheets, were change controlled by the business an imported into the system when they were approved. I considered this design a form of a visual language and the real beauty was that it did not require any re-coding of business rules, which did change quite frequently. The developers did not have to be re-writing any business logic as the rules changed.

The back end was Java and TCL based built on a graph database. Not super fast but super easy to understand and train up new developers.

It was quite successful and ran all sales contracts for for several years with billions of dollars of contracts passing through per year. I lost contact with the teams so I'm not sure how long it survived but I know that SAP charged millions of dollars trying to build a solution in their systems but could not get one working at a reasonable price.