Here are some reasons why Resolver Spreadsheet is awesome:
1. It produces Python code. There is no particular reason why I couldn't virtually cut-and-paste something from the spreadsheet as an algorithm in my application. Vice versa, there is no reason I couldn't "prove" an algorithm to a co-worker or supervisor by setting up some sample runs and graphing them.
2. It produces Python code. You can edit it to change the semantics. If you like coding, you can do it!
Things that are not as awesome:
1. It only runs on Windows
2. There's a 31 day evaluation. I understand why, but I still find evaluation periods annoying and too short. If I could have a 6-month evaluation period, then I'd be happy.