so, you have gigabytesper second of disk io, and the game relies on the couple of megaBITS of internet bandwidth most people have to stream textures? As opposed to downloading and installing them once as an update…
you don’t compare fpgas to just any emulator. But you can compare them to gate level simulators (not emulators). The ones that take a beefy 4GHz+ pc just to emulate a gameboy at 8 fps. But also guarantee 100% accuracy and compatibility with all games. Fpgas can do that in real time.
whoops, one of our developers slipped on a banana peel and accidentally hit all the right keys, over the course of a couple of hours, to accidentally implement ads in the game
that only really works with deterministic systems though. You could do that with a 6502 or simple systems because you could perfectly predict what the state of the system would be in just by replaying inputs. everything up to predicting all cache misses.
consider a badly written game on a modern console (remember that save states should work for any game) in which physics is tied to framerate. Follow the chain… framerate depends on system speed… which, indirectly depends on the ambient temperature (a console running in a hot climate would throttle earlier than one running in an air conditioned cool room). And because modern systems execute more than one process, it also depends on what else is running (were you downloading a game in the background, slowing down the game ever so slightly?) or unpredictable things such as interrupts on certain system timers. And the list goes on and on. Even if the game didn’t have physics depending on framerate, differing deltaTime on each frame means different floating point rounding errors happen, which could accumulate over time.
So in this case, replaying inputs does not get you the exact state. you were in. there are just too many variables.
system state is not the same as a save file. System state is the cpu registers, the process’ entire memory space (because you don’t know what the game might do at any point) gpu context, etc.
edit: example: the save file for older games was measured in bytes. System state is much larger han that. It contains everything not just what the developer decided to allow you to save.
yeah this can only work if implemented by the devs. The only reason this can be done for some older emulated games is that there is only a megabyte or two needed to capture the state of the entire system. Not several gigabytes.
re plague tale 2: I found that it crashed (more like hung, process was still running) whenever I opened one of those screens. It seemed like the crash occurred for me when I scrolled through options on those menus too quickly. ex: switching to a different skill while the small preview video clip from the first one was still loading. I ended up scrolling really slowly through those trees
there is no such thing as “idling” in a game, when viewed through the lens of software engineering. Even if you aren’t giving the game any new inputs, the game is still doing the work of rendering the screen. Calculating a turn is actually only a small part of the process.