Thanks! I looked everywhere, except these Forums.. not a very smart move on my part :P

Funny thing is that many people don't really think about the theme of their work, which is why they're having trouble describing them in a concise manner.
Trying to come up with a one sentence description about your game can really help you nail down what exactly it is, that makes your thing interesting, which in turn can help your creative process. It's also a nice opportunity to try to come up with unique descriptions that don't rely on you comparing your work to someone elses'.

Also the Elevator pitch (at least as far as I understand it) is meant as a gateway to convince people to listen to your more in-depth explanation. Sure, it's shallow but most conversations with strangers start on a very shallow level. Also just because you can describe a thing on a superficial level, doesn't mean that the thing itself has to be superficial. It's all a matter of perspective.

Totally agree. For me you either have something new that's hard to explain in "one sentence" or you do a remix(because everything is a remix) and go like "My game is Mario Kart meets Dungeon Keeper but with mature themes."* which is not so interesting as "one sentence".

For me theme is a deal breaker. Let's do a shooter. Nah. Let's do a cyberpunk shooter? Fuck yeah! Lot of people in gamedev think that setting is just something you pick after deciding what game you want to make. Like you decide to go for a walk and just need to grab hat or cap. No, you grab a fancy fedora and it's not just a walk it's a stroll down the Al Capone's Chicago ;) If we strip shooter games from themes there is almost no telling from one another. Setting adds flavor that speaks to people, that helps them identify with piece. Meet lots of people who tend to get obsessed with "game needs to have unique mechanic" or that just don't think that games could be about specific feeling/atmosphere. But it's another topic about games with no gameplay.

*pitch generator