What are the benefits of making a new engine and throwing away 10 years of progress? I mean I'm a bit sceptical about the whole thing *shrugs*
Over 10 years, you don't just make progress, you try and learn new things each time you are building an engine.
But when you are building a new engine upon another one, an old one, then it's just iteration, and you still have to deal with old functions which could not be okay with the new platform you are building your engine for.
Sometime, it's better to start everything from scratch and use new tech and code to optimise your engine and create tools that are perfectly adapted for your needs, actual and future.
One example, which is not a game but a website, but the idea is the same :
http://www.halodestiny.net/
Since 5 years, we are using a CMS called PHP Fusion. It works fine and it was a really good start for us 5 years ago when we didn't really know how to build our own web platform and tools. We have simple tool to write our articles and let our users post comments and messages accros the website and the forum.
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But since, we learned a lot and we want to do more right know. We know how to deal with our ambitions, like we want a website which will be responsive (aka usable on mobile), and we want to use our datas to create mobile and web applications.
We could still use PHP Fusion, but we would have to deal with codes and functions that are not thought for our needs. We could change these functions and make them work on mobile, but it will only be some tricks and we could not have the perfect tools we need for what comes next.
So we have decided to start everything from scratch and create our own technology to run our website. It was faster to create our new tools to support our vision and our needs than adapt PHP Fusion.
We won't lose all the progression we get since 5 years, we learned from it and we can recreate these act of progress quicker than ever thanks to our new tools.
As a last example, I should show you how we actually write articles on HDi right now and how we will write articles with our next version D7.
The elements are the same, a text area and a publishing button. Now we can edit our text in a simple way, add pictures with a simple drag and drop. Before that, we had to go into a specific section of our administration to upload picture, then copy/paste the picture's link and put it in hard mode in our article using HTML (web layout language).
Maybe my presentation isn't perfect, and be sure that drop a old engine is not a way to lose 10 years of progress. Sometine, you HAVE to drop your old tools and create new one to accompany your vision.
And usually, it is faster to create new tools than deal with an old and inappropriate one.
Be sure, and trust me, that if 343 Industries have really create a new engine, it is for the best.