I'm probably wrong but without too much thinking, I'd say Arial... The easiest would probably to check the code... What's the online game you're referring to?

I thought about that but the first picture is from 2006-2007 and the other 2007-2008, nowadays it's a different font.
What bugs me in the first picture is that little black area surrounding the letters that I don't know if it's made by the game or it's the font itself. And in the second picture the number 3 is always different to the fonts search engines suggested.