Why do some games have sounds with various bitrates?
Because the sounds in those games vary in quality. After ripping or recording each sound, I resample them to the smallest standard sample rate before they suffer any noticeable loss in quality, in order to keep the file sizes as small as possible. Depending on the purpose, you may even want to edit them yourselves using software such as Goldwave. For example, a 16-bit, 32 kHz sample sounds good, but for a Gameboy-styled fan-game, it would sound more fitting as an 8-bit, 22.05 kHz sample.
