WrittenRealms is described as 'lets you build and play narrative adventure games. Features a rich combat system with four playable classes, each with distinct skills and character customizations' and is an website in the Development category. There are seven alternatives to WrittenRealms, not only websites but also apps for a variety of platforms, including Windows, Linux, Mac and Android. The best alternative is Twine, which is both free and Open Source. Other great sites and apps similar to WrittenRealms are Ink by Inkle (Free, Open Source), textadventures.co.uk (Free), Playfic (Free) and Interactive Fiction Archive (Free).
textadventures.co.uk is a community of interactive fiction game makers and players. All games here are either playable in your web browser, or as an app for your smartphone or tablet. Almost all are free, and you can even make your own, using...
Playfic is a platform for writing and playing interactive fiction. Interactive fiction (aka "text adventures") is a genre of game that uses no graphics or sound, but instead, uses text to tell a story in an interactive world.
The contents of the IF Archive -- including thousands of text adventures, text adventure development tools, articles, essays, hint files, walkthroughs, jokes, and sly references to Greek politics -- are contributed by the interactive fiction community, past and present.
The Interactive Fiction interpreter in an Electron shell Lectrote currently supports: Glulx games (.ulx or .gblorb), as produced by Inform 7. Z-code games (.z3/.z4/.z5/.z8 or .zblorb), as produced by Inform 7 or earlier versions of Inform. Hugo games (.hex).
Yarn Spinner is a tool for creating interactive dialogue for games. Write your conversations in Yarn, a simple programming language that's designed to be easy for writers to learn, while also powerful enough to handle whatever you need.