I'm not sure the 'hollywood high concept elevator pitch' of 'it's like X with Y!' is the best way to approach this as you're selling to a prospective audience, not a prospective producer.
So that said, look at it like any other product:
1) What's the USP (Unique Selling Proposition) on AW? What makes AW different (and better!) than other RPGs, and specifically other RPGs with a post apocalyptic setting? What can you do with AW that you can't do with any other game? As a player, how's the AW experience unique and only available via AW?
2) Define the target market. In terms of their preferences, what elements does AW share with stuff they already like? This could be media (books, movies, TV shows etc..) other apocalyptic themed RPGs, an interest in indie games, or games authored by Vince Baker, whatever. Just map the connections.
Answer those two questions and you should have the elements to highlight to promote sales/interest when someone asks you about the game.
For me, I see: The game has an 'R Rating'. It's by Vince Baker, author of Kill Puppies For Satan, Dogs in the Vineyard, In A Wicked Age, and Poison'd... The playbooks definitely qualify as unique packaging, and totally remind me of the little pamphlets certain religious groups distributed at one time, specifically the Chic Tracts. Mechanically, it reminds me a bit of 'Go' - it's simple to learn how to play, but actually playing reveals a complexity and depth that keeps things interesting. ("The further you 'go', the deeper it gets.)