This isn't true. It has some significant changes, but still feels like the original. They nailed it.
There is new voice acting, and voices are effected by your position to the speaker. They improved the leveling system. They added sprint. The combat feels similar, but is a lot less janky. Of course the improved VFX and SFX. There is probably other things. But it's definately more than a remaster. It feels like a remake.
Yeah apparently Unreal for rendering, overtop Gamebryo