I just received a driver update, and it says that I get the "best day-1 gaming experience". I think that it should read day-one, as day-one is not stated as a specific amount of time, just the release day of the game.
If it was talking about, like, fifth day of the game (example: Unfortunately, hacks were already released for the game on day-5.), I'd expect that.
The text reads:
Prior to a new title launching, our driver team is working up until the last minute to ensure every performance tweak and bug fix possible makes it into the game Ready driver. As a result, you can be sure that you'll have the best day-1 gaming experience for your favorite new titles.
Best Answer
Technically, the English writing rule is that you should spell out numbers less than 10. So, looking at the sentence from only that point of view, you would be right ... "day-one" would be correct.
However, it seems to me that the writer is drawing attention to the claim that the team is doing everything possible to ensure the game is bug-free on release day. From this point of view, the writer is advertising, more than just informing. When advertising, the writer can really take whatever liberties she/he wants. In this case, the writer wants the reader's eyes to focus on "day-1," which works better at drawing attention than "day-one."