Rex Dark said:
It's been anounced in 1997...
Unlike HL3 which hasn't been anounced at all.
I'm still waiting for episode 3 though...
Also, changing an engine shouldn't take much work, it's not like you're recoding the entire thing.
You might break you ctrl, C and V keys though...
The logic for the game itself should be pretty much the same.
Probably not many changes.
Might be a pain if you have to change your function names for whatever the new engine uses though...
Well, that, and some more corrections.
It's not like the game has to be completely different from before the engine change.
Well, unless you change your programming language... (Like suddenly switching from C++ to VB.net, but Why would they want to do that?)
It's actually a fairly significant change, and not one you can copypasta your way through.
If you know anything about programming, you'd know what an API, or application programming interface is. What an "engine" is, in its most basic form, is an API to translate the data (models, damage/health calculations, etc) into a playable game.
When you change engines, those API calls are all drastically altered. Which means you would need to go through
all of your code and adjust the method calls/signatures to match the new engine's set-up. Most complex programs have upwards of 300,000 lines of code (and it wouldn't surprise me in the least if most modern games are 1,000,000+). It will take a lot of time to transfer the code over.
It's most certainly not a quick or easy transition.
Edit: You are correct in that the base logic of the program won't change, but the process to follow that logic can be, and usually is, altered drastically.