I have a specific idea in mind for a game engine. I want to use a simplistic 3d model of the game world, projected orthogonally for scenes with a moving camera, or with perspective for static scenes, to create a lighting and shadow stencil which will be composited with a pre-rendered 2d image of the scene along with 3d rendered character models to create an effect similar to what you find in old ps1 era jRPGs (final fantasy 7 - 9, chrono cross etc.) but with much better lighting.

I will eventually want to port it to android, ios and windows desktop computers.

So basically i just would like advice on what tools you'd use for creating this. OpenGL from scratch? Some kind of existing framework or engine?

Thanks

Unity can do iOS and Android for fairly cheap ($400 for each). Free for Windows, so you can develop the game for free and port it to mobile later.

UDK can do iOS for $99 & 0% royalties on profits up to $50,000

I'd recommend against going with OpenGL from scratch unless you have a very compelling reason not to. Saving $800 on Unity is not a good reason; at US minimum wage it would take you about 110 hours of work to make that much, and you would spend WAY more than that starting from scratch. Plus the opportunity cost. Plus you are much more likely to give up. Best course of action IMO is to get a free Unity license, make your game, and then invest in the mobile licenses if you want to.

Yes creating a game engine is a lot of work! 800$ seems reasonable... if there is a way i can test the android / iOS performance before sinking the money to deploy it that would be amazing.

But regardless, quality reply! Thanks!

I believe Unity has a trial for the mobile components, you could use that to test (although I assume to use it with iOS you would still need to get the $99 Apple developer license).

I assume to use it with iOS you would still need to get the $99 Apple developer license

According to their FAQ's you do

gamekit for all os. Sure apple wants 100 bucks...they might even sue you if you forget about them. Hence forget ios.

Saving $800 on Unity is not a good reason; at US minimum wage it would take you about 110 hours of work to make that much, and you would spend WAY more than that starting from scratch.

Eh? At Federal minimum wage ($7.25), assuming full-time work, your net yearly income is ~$15,080. This places you in the 15% Federal tax bracket. Ignoring the potential and likely State income tax, for 110 hours of work, you'd receive $677. This does not count the fact that you are also likely paying for:

1. Rent
   
2. Auto Insurance
   
3. Food
   
4. Gas
   

$800 is a lot of money when you are living on minimum wage (and that assumes that you even get 40 hours, which is not likely anymore).

AFAIK, if you have a jailbroken iDevice, you can test your App on it by transfering it from your PC. IIRC, to DEPLOY it you need to pay the $100.