I had direct experience of this. I knew a dev-team working on a CDi (don't laugh!) version of Namco classics, including Galaga. They were given some technical info about the games, but had to reverse-engineer the Galaga attack wave patterns by pausing the game and tracing them on the TV with a felt-tip pen! It was a very painstaking process.juice wrote:Also, many developers were held to ridiculously tight deadlines (Pacman and E.T. being two prime examples; Ghostbusters is another) and as Merman has noted, at least in the UK, technical information for "home computer" porting ranged from little to none, so the game mechanics had to be reverse engineered by observing the arcade game in use. And even this was relatively uncommon; this month's Retrogamer has an article on the development of TMNT; the Spectrum/Amstrad developer had no technical information provided to him and was given just one day to play the arcade game; aside from this, all he had was a video tape of someone else playing the game!
I've also seen other devs work on arcade conversions, and if they're lucky they'd get an arcade cab to study, but they wouldn't get things like source code, or graphics dumps.