The first three phases
It's too early to guess when pieces of the Tenterhook platform will see daylight, so I can't generate any sort of traditional roadmap yet. But I can describe the three major phases that lie ahead:
Foundations (in progress)
I've found that development goes much smoother after I've converted ideas into documents and mock-ups. Those ideas have been baking in my head for a while now so it won't take long.
Ramping up on technical goodies such as AngularJS will be an ongoing process, but the good news is I'm diving into the same things at work so it's a win-win.
Development - Web
When adventures can be built and run on the web, I'll release a sample adventure and launch the Tenterhook web site. There will be loads of resources to help people get up to speed.
Development - Windows 10
The beauty of this phase is that the hard part will already be done. Windows 10 clients (desktop and/or phone) will be able to fetch manifests from the Tenterhook Web APIs, so all I'll need to do is build the C# version of the scripting engine.
After that I'll build a Universal App template solution, which will enable developers to rapidly create Windows 10 adventures.
If the third phase goes smoothly it'll prove the platform is as extensible as I'd hoped. If that's the case, who knows... it's entirely possible I'd take a serious look at Android and/or iOS.