Inform itself is a free download. It produces works playable on a vast range of computers: distribute these free or for profit with no rights implications or financial obligations to the author of Inform. Convenient publishing features include help with drawing maps, producing websites, cover art, bibliographic data, walkthrough solutions and more.
In the left hand panel of the window, simply type a description of the work in natural language - in English sentences, that is. Click the Go button, and Inform replies in the right hand panel: if it finds mistakes, these are thoroughly explained - for instance, with examples of correct and incorrect usage - but if all is well, the game begins playing. It can be explored just as a player of the final work would explore it.
Should you play for a while, say, getting 20 turns into the story, and then find a finicky mistake - or something that could be improved - simply amend the source text back on the left and click Replay: then watch as your steps are retraced back to where you left them, and resume.