Game sound effects are hard. As someone who's tried recording sound effects with a crappy microphone (including making laser blast noises with my mouth), there came a time when I sat down at my computer and just started at, puzzling over how I could convince it to make the sounds I wanted for my game.
It wasn't until several years later that I found bfxr. This is a marvelous little free tool made by increpare, based on an older program made for a Ludum Dare called SFXR.
It has a dozen or so preset sound buttons, like jump, coin pickup, and explosion. Every time you click one of these, it randomizes innumerable confusing settings to bring you a slightly different clip each time. You can then, with the click of a button, export the generated sound to a .wav file. Easy-peasy, as they say.
You can, of course, tweak that aforementioned plethora of settings to get the sounds you be exactly what you want. I've been using bfxr on and off for several years, and most of them are still a mystery to me, but that's okay. You'll want to try out the mutate button a good amount, and watch how the sliders change. Then, slide a slider at a time and see what happens. Be aware, though: the sliders are very sensitive and it's easy to get your sound irretrievably unrecognizable. Make sure to save sounds you like before messing with them.
The end result of all this, of course, is some pretty nifty lo-fi 'bleep-bloop' sound effects to use in your game. I don't necessarily recommend using this if you're making a fully 3D RPG or realistic FPS, but you still night be able to wrangle some button click sounds out of it even if you are.
However you use it, the takeaway here is that bfxr empowers you to make sounds yourself. They're entirely unique, and an excellent starting place for budding sound designers or game developers who don't know their way around a microphone (like me) or who can't find the exact clips they need on a site like freesound.org or freesfx.co.uk.
So, without further ado, check it out now: BFXR!