What's involved in creating an iPhone app?

I have an idea to port an 80’s-era, turn-based, strategy/war game that I still enjoy and that is still available for DOS and Apple ][ emulators. The last time I programmed anything was probably in BASIC in the late ‘80s. Other than buying the SDK, what else would I need to learn to do this? What kind of time is involved? I believe it is abandonware, but what about licensing/rights issues? Who wants to be my Huck Finn?

edit: it looks like the original publisher was acquired a few times over ending with Ubisoft, which has retired the original brand name.