I'm new to speed running, and I like the idea of having some World Records. The thing is, I see some leaderboards that are kind of empty, and I could grab the World Record in all of them. Is that frowned upon, or am I over-thinking this?

Thanks in advance

You're overthinking it. Run what you want to run.

That said, getting a free world record in a game that you otherwise don't really care about may not be as satisfying as you're expecting it to be.

what @ShikenNuggets says is true, but it's not frowned upon. if you really want a world record, make sure you actually want to play it, or you'll give up sooner than you think. if yes, go for it!

I'd say to find games that you want to run. If there's empty categories, then you should go after them.