Well, if you outsource graphics and sound and if the idea is nice, a one good one man game should be possible.
Have a look at http://www.snood.com
for example: It looks quite simple and could have been a one man job, graphics are not great, but as far as I know tons of people are playing snood like hell!
Maybe it's not that title that hit the cover page of all game magazines, but you can make some money with it.
Slashdot had nearly the same story, look here: http://developers.slashdot.org/article.pl?sid=03/01/18/1452229&mode=thread&tid=127