Game Titles. Do they have to be 100% unique? Options

[Broken Aesop]

A question has been on my mind for the past few days, and I've decided to submit it the public for consideration.

When I named my game, I wanted something simple that encapsulates the dungeon crawling concept. I thought about something that basically says what you do in the game...you descend. I thought, damn, too bad there's already a game called Descent. So I added an extra syllable to make it a word that pretty much means the same thing and called it a day. Descension is an ok name, but Descent is still better. Now I'm thinking...since my game has nothing to do with space ships and shooting lasers and stuff, could I just call it Descent?

I've felt like this would be horribly unoriginal, but sometimes things that are original just for the sake of being different from something else just aren't that good...like trying to make a toothbrush out of a pine cone just because Crest already uses plastic and bristles. Then I realized zestygrapefruit has a game called A Nyght's Tale, and it has nothing to do with dream wizards flying through rings or whatever. Nobody has accused him of "stealing" the name. It fits the game, and that's all that matters. And that's what I'm starting to realize...I think as long as you're not pretending hugely popular titles like Doom never existed, and making RPGs about a family of heroes who just so happen to be known as the Super Mario Brothers, then I think it's ok to use a name that's already been used. Especially if it's from another genre. Correct me if I'm wrong on this.