"May even explain why Hedgehog Engine 2 isn’t apparently as robust as Hedgehog Engine 1" What have you heard about it? I have poked around a bit with HE2, so I would like to know what strikes you as "less robustness"
Unfortunately, this isn’t really something I can talk about at length, because I’m not someone who is familiar with the depths of this. All I really know is that:
To start, Hedgehog Engine 2 provides some legitimate improvements to lighting detail in different kinds of textures. There were these images going around:
I don’t know enough about shader technology to tell you exactly what’s going on here, but the results are obvious enough. Hedgehog Engine 2 seems to incorporate some kind of texture self-shadowing in to its global illumination pass.
But what I also know is that Hedgehog Engine 1 was at its most robust in Sonic Unleashed, and after the engine designer left, Sonic Team gradually began stripping out features for being “too expensive” to render (read: they made the framerate bad).
This makes some amount of sense, because the framerate in Sonic Unleashed, particularly in the last few levels, could get pretty bad. There’s a few places in Eggmanland where the framerate can get down to single digits. Sonic Generations, which uses an “updated” version of Hedgehog Engine that’s a bit more conservative features-wise, maintains a pretty solid 30fps on console a lot better.
But Sonic Team didn’t stop there. They kept stripping features out, because they got it in their heads that Hedgehog Engine should hit 60fps. So all the beautiful and bleeding edge lighting technology, all the fancy material rendering, all of it got stripped out or simplified for Sonic Lost World. From what I remember hearing from people in the know, Sonic Lost World will never be able to render levels from Sonic Generations because it’s missing too many features.
I believe Dario (of Unleashed Project fame) ported over Jungle Joyride to Sonic Lost World, and it crushes the engine. Completely wrecks it. You need to have a PC far in excess of the expected system requirements to even play it, because it was not designed to render something like that. Just completely butchered.
From what I remember hearing, Hedgehog Engine 2 is very similar to the same version of Hedgehog Engine 1 used in Sonic Lost World, with some of the more “expensive” features added back in -- but not all of them. And some, like the lighting engine, were obviously changed or replaced entirely.
I realize this isn’t a lot of hard information, and I’m sure I’ll get a reply on Twitter from one or more people clarifying my half-remembered truths. But that’s the general impression I have been left with: HE2 is better in some ways, but worse in many others.