I have no plans to create my own videogame (you're welcome), but that hasn't stopped me from playing with ChipTone, an extremely cool videogame sound effects tool, all day. It's like a little sound board with SFX for coins, jumps, zaps, explosions, 1-Ups, and other video game sounds. And there's all sorts of ways to tinker and mutate the sounds so you can create the SFX of your dream game.
Or, like me, you can just sit there poking it to make cool 1-Up sounds that tickle the pleasure center of your brain. Ahhh, that feels good. Just one more 1-Up. Mmmm! Perfect. Okay, maybe one more.
You can play with ChipTone to your heart's delight and easily save your effects as wav files right here on it's Itch.io page in your browser. You can also download it, and why not kick the developer a few bucks if you like it? It's an exceedingly neat and easy to use tool, and the developer states that the sounds you generate are completely free for you to use in a game, video, or any other project, casual or commercial. Pretty dang nice!
Give it a try, even if you're not working on something that needs videogame sounds. It's fun just to poke the buttons and see what comes out, and then start messing with the various knobs and dials to see how you can make a cool sound even better. There's a sound sampler and sequencer addition planned for the future, too.