I used the code from OpenRCT2 as a guide to remake the game from scratch with the original assets, but the game also allows saving and loading of saves and coaster designs from within the game. The files are obviously different from the PC version, which I why I said I hadn't yet looked into loading the files from the real game. If I can't get it to interpret the original .TD6 and .SV6 files, I may be able to work out some sort of conversion utility. But it's not a priority; the next thing to work on is the audio.
Okay. I'd really like to see someone do something similar to this with Age of Empires which is why I asked.