m_kiewitz: ScummVM has its own SCI interpreter, which gets around almost all timing issues already, and all sorts of known game bugs are patched on-the-fly, which means you don't need to use patch files at all and those on-the-fly patches even fix various translated game versions as well, because the patches are dynamic. It's sort of working like virus scanners are working, they are using code signatures.
dtgreene: Is there, by any chance, an option to disable the on-the-fly patching, in case I want to play the games as originally written (complete with bugs and all)?
ScummVM does not patch regular non-problematic game bugs like for example getting unlimited skill points in Quest for Glory games. That's obviously a glitch, but not a problematic one.
It patches stuff like:
- crashes
- "Oops, you did something that we did not expect"-errors (which is basically a SCI VM crash)
- timer bugs/issues, like the Space Quest 4 escape sequence with the sequel police
- game breaking glitches (like Leisure Suit Larry 5 green card bug)
- regular obvious glitches (like for example saving + restoring the game while driving a car in the Police Quest 1 VGA remake, this normally will result in the map not being shown properly, you have to drive off that screen for it to work again - or for example QfG 3 not importing QfG1 characters properly, or QfG 3 not exporting some characters properly)
- special new features like for example Speech + Text at the same time for games, that did not support it originally. Like Laura Bow 2, Space Quest 4 and King's Quest 6. But it's added as a 3rd option. No one is forced to use it.
- effectively bugs, that just worked by accident in the original interpreter, but don't work anymore in ScummVM, because ScummVM checks all sorts of things. The original interpreter allowed bad memory access, using uninitialized variables, calling kernel functions using wrong parameters and so on - not patching/fixing those would result in signature errors, something that did not happen in the original interpreter.
There should not be a reason of wanting to have those kind of issues happening, because most of the time you would simply get an error message or a corrupted / frozen game.
So for now, there is no way of disabling those script patches except by modifying the ScummVM source code and compiling it by yourself. If there was the need of wanting to have a specific bug to happen, then such an option could be added officially of course. I just looked through the script patches and I can't see a single one.
Situations, where the game is simply unwinnable, will not be patched, because that's working as designed. But for example the Leisure Suit Larry 5 limo bug however was fixed in multilingual versions of the game by Sierra and it's obvious that it was not meant to happen.
The ScummVM SCI VM itself already slows down all sorts of games, otherwise you would have to for example do 2000 or maybe 20.000 push ups in Larry 3, because the game calculated the required amount of push ups by checking the speed of the computer and no one thought that computers could get faster and faster. Or maybe no one thought that people would still play those games 20+ years after they got released. I doubt anyone would want to do that many push ups :p
