[Sirius-R]

Recently I've been struck with the idea of hacking Test Drive 2 for Mega Drive/Genesis with the purpose to add more variety to the game (3 cars, 3 scenarios and 3 short music tracks get boring fast IMO). However, I never dealt with ROM-based games, so I have no idea what to do. For now I'd like to see the game's structure, to see if I can actually add anything (like in those fancy Dune 2 hacks with six houses to choose from) or I'm limited to texture editing.

Thanks in advance.

[Jorpho]

If all you want to do is look for uncompressed graphics, just open up the ROM with Tile Molester.

Anything beyond that will probably require advanced knowledge.  If you've ever used a debugger before, there's probably at least one Genesis emulator out there with a suitable debugger, though I wouldn't know which one offhand.

[Sirius-R]

I remember opening the ROM with Tile Molester - all I've got was pixelar garbage.

[Jorpho]

Then there is little to be done, assuming you selected the right graphics mode and weren't using an interleaved ROM.  The graphics are probably compressed, and since Google doesn't suggest it uses a common compression algorithm, that means you'd have to analyze the code and reverse-engineer whatever algorithm it is using.  This is not trivial.

[Sirius-R]

Sounds cool, especially considering that my coding skils are almost null, hehe.