Recreating a game in a different game engine. Thread

Hello, IndieDB.
I was just wondering how difficult is it to recreate a game in a whole different game engine. For example; I made a game in Unity, then I decide to do the exact same game in, let's say, Blender Game Engine. How difficult would that be and is it possible to recreate the exact same game for reasons like cross-platforming or whatever?
And to add, let's also say I have thorough experience in both engines.

Thank you.
-Manny.

If you know both engines in depth then why don't you know how your game will work in both engines ?

It's almost impossible to duplicate it in a different engine. Ignoring the asset side, engines handle inputs/outputs differently and those little things can make a huge difference in how a game "feels".

I know BGE pretty well and I am considering moving on to Unity because it can actually publish stuff. Why would you migrate from Unity to BGE? AFAIK Unity has better performance and support with multiple language and platform options. BGE has no publishing options that Unity doesn't.

I would also agree with TheHappyFriar. If you already polished the controls, shaders, UI, colors etc you will have hard time getting the same result on a different engine. Most likely you will end up in trouble and end up doing stuff in a different way.

Okay, forget BGE and Unity. Let's say Engine-A only works on Windows while Engine-B only works on Mac, knowing that Engine-A has the approximate same performence as Engine-B.
Let's say I made my game in A and I want my game on Mac, the question is; will I be able to recreate the same game that was created in Engine-A in Engine-B?
I think a while back I read an article about a game and it said: Android Version : Custom Built, iOS Version: i.e. Engine-C.

Sorry if this question is kinda weird and confusing.

Thank you.
-Manny.

Edited by: Dahamonnah

Well sure if you spend time on it. But depending on the engines you might need to code everything from scratch. Also the closer match you want with shaders and controls, the more time required (increases exponentially).

Most teams commercial or not will not go for this, instead they choose the programming language and software that is able to port to desired platforms with relative ease if not directly. In the past the dev options were much more limited than today and you needed to really pick if you go with PS, Nintendo or Xbox with PC sometimes pairing with the latter 2. Mac was really rare due to obvious reasons.

Nowadays the choice is pretty simple for small companies: Unity does it all pretty much. The minor downside is that it doesn't support some of the OS-specific libraries so you might end up doing a bit more coding (some of which might be really troublesome like speech recognition) but in the end you'll be able to port anywhere easily.

It definitely it possible to do that and how difficult it might get is depending on what problems each engine comes with. If engine A can do the exact same things like engine B without any problems, then obviously there's no problem in doing it. How difficult it might get is therefor only depending on the limits or ways how the specific engine handles input/output etc.

If you have your software planned out properly with all sorts of diagrams and such things, it's relatively easy to do that, if the engine doesn't come with too many extra problems. Also, it's hard for us to tell you how difficult it is, because we have no information about how good you are at what is required to do here. If you're a beginner it's probably pretty difficult, but managable.

If you want your game to function on multiple platforms, why not go for a cross platform game engine?

That's the simple solution.

The reason id always did straight C/C++ code (with some minor OS specifics) was so that the version of Doom (for example) that was coded for BeOS will also work on Windows. The languagues function near the same on every piece of hardware/OS but there's lots of shortcuts one can do to make things to faster on a specific piece of hardware/OS. That results in more dev time. That's why OGL won out over 3DFX, it was more hardware compatible, 3DFX-GL was for a specific companies cards. Took more dev time to code for OGL (to run on non-3DFX cards) and 3DFX-GL.