I like the idea, but I didn't like losing after a few words. Now it might just be me not being good at losing, but who is?

Maybe the game can always progress to the next word with your total score being reduced. So if you get all within 30 seconds you score 18/18. That way everyone can play the whole game and share with their friends how far they got:

|X|o|X|X|X|o|o|o|X|X|X|X|X|X|X|X|o|X| 13/18

Yeah, but also, is it really "18 words" if you don't get there?