Thanks @MarkTr ! 
For anyone reading this thread who is unfamiliar with Sharptools, it is a third-party app that offers both a dashboard and a Rules engine. The rules engine has a lot of advanced features and has a nice visual interface, which is really easy to use. It will run in the cloud, but then so did The old smartapps, so most people are OK with that. They have both a free tier and a paid tier with advanced features. The paid tier is $30 a year. Very popular in the community, and it already works with the new architecture.
Anyway, you can read more about that, and other options for replacing the old groovy code in the following thread