Eli5 why is Video Game emulation so difficult? And how do new glitches come about?

Question

Eli5 why is Video Game emulation so difficult? And how do new glitches come about?

In: 54

Answer 1

Different developers program in different ways. Let’s look at FPS, Frames Per Second, as an example. This is how many times the game shows you a new picture every second.

Dev 1 might make a game at 30 FPS and tie the physics to that game. This means if the FPS increases the game speed increases.

Dev 2 might make the game have unlimited FPS, meaning that the FPS will go as high as the hardware allows, but since all, say, GameCubes, have the same hardware, the dev knows the FPS will mostly stick at 30.

Now let’s try to emulate each of these games. Let’s say the GameCube emulator lets the game increase FPS to what the hardware allows. The computers people are using to emulate today are generally much better than the GameCube was.

Game 1 stays are 30 FPS and works fine.

Game 2 now has 120 FPS sometimes, but drops to 60 FPS sometimes, or 30 FPS sometimes. Since a PC will have multiple process on-going this will change the frame rate to however much the computer will handle at the time.

So one game works fine, but one has a constantly changing frame rate, which is very annoying. To fix this let’s say the emulator changes it so all games now run at 60 FPS.

Game 1 now runs at 60 FPS, but since the physics were tied to frame rate, the game now runs at double speed.

Game 2 now runs at 60 FPS, and works fine, but some people have good enough computers that were able to constantly run it at 120 FPS, and are now upset the game doesn’t run as smoothly.

All of this is to say that games are software made for a very specific hardware. Every GameCube game was made just for the GameCube. Trying to make that game run on PC, where each user will have slightly different computer, and also want the games to run better than they did originally, leads to plenty of glitches. This is why new emulator glitches come up, because any system wide change will effect some game. Fixes will need to be made on a case-by-case basis, which is very time consuming for people who often aren’t getting paid to make these emulators.