Ive never done any real game coding, just a really simple card game, in C++, You might heve to ask yourself a few questions what do you want to code in? Jarva, Visual Basic, C++, etc etc as i'm sure that this will influence your game as you will need to learn the language, also if its for a portfolio you might want to see what studios use to code as theres no point leaning a language that isnt used in the sector that you want to go into.
Othe than that when you settle on a language then I would suggest looking to see if theres a website on the subject, and go from there.
Dont know if this helps or just raises more questions!
I think Joopson and MattheMan were making a game of some sorts, maybe they could point you in the right direction??
"No pressure, no diamonds" Thomas Carlyle