All sound files are Public Domain (CC0).

They can  be found at this locations:

https://opengameart.org/content/rpg-sound-pack
https://opengameart.org/content/gui-sound-effects
https://opengameart.org/content/5-break-crunch-impacts
https://opengameart.org/content/platformer-sounds-terminal-interaction-door-shots-bang-and-footsteps
https://opengameart.org/content/metal-interactions
https://opengameart.org/content/8-wet-squish-slurp-impacts
https://opengameart.org/content/level-up-power-up-coin-get-13-sounds
https://opengameart.org/content/50-rpg-sound-effects
https://opengameart.org/content/door-open-door-close-set
https://archive.org/details/CameraShutterSound (https://opengameart.org/content/camera)
https://freesound.org/people/mccormick_iain/sounds/371094/
https://opengameart.org/content/35-wooden-crackshitsdestructions
https://freesound.org/people/qubodup/sounds/159725/ (https://opengameart.org/content/catching-fire)
https://opengameart.org/content/steam-release-sounds
https://opengameart.org/content/synthesized-explosion
https://freesound.org/people/j1987/sounds/111325/ (https://opengameart.org/content/simple-fuse-sound)
https://opengameart.org/content/fantasy-sound-effects-tinysized-sfx
https://opengameart.org/content/58-random-sound-effects
https://opengameart.org/content/teleport-spell
https://opengameart.org/content/68-workshop-sounds (https://opengameart.org/content/fast-hammer-sfx)
https://opengameart.org/content/4-space-portal-sounds
https://opengameart.org/content/magic-spell-sfx
https://opengameart.org/content/win-sound-effect
https://opengameart.org/content/electric-buzz
https://freesound.org/people/LordForklift/sounds/448394/
https://freesound.org/people/Breviceps/sounds/448080/
https://freesound.org/people/Glitchedtones/sounds/322432/
https://freesound.org/people/sharesynth/sounds/341247/
https://opengameart.org/content/stonecutter-sfx
https://opengameart.org/content/hammer-on-anvil
https://opengameart.org/content/20-rustles-dry-leaves
https://opengameart.org/content/misc-sfx-pack
https://opengameart.org/content/100-cc0-sfx-2
https://opengameart.org/content/breaking-rock