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SurveyJS
Open-Source JSON Form Builder to Create Dynamic Forms Right in Your App. With SurveyJS form UI libraries, you can build and style forms in a fully-integrated drag & drop form builder, render them in your JS app, and store form submission data in any backend, inc. PHP, ASP.NET Core, and Node.js.
Recently The Modding Tree has become more popular. It allows you to quickly create games like The Prestige Tree, while still leaving room for customization.
If you're developing for Web, it can be nice to use a front-end framework like Vue or React. I think most devs here prefer Vue over React, but they have very similar capabilities. Websites are also fairly easy to port to mobile (albeit with not so great performance usually).
Now for some self-promotion, I've created the Incremental Game Template. A bunch of scripts that will help you implement stuff like Statistics, Achievements, Save/Load, Settings, Currencies, and much more :)