I had this too, when I first published my game I couldn't see it on the games list, even with some pretty specific filtering. But suddenly after maybe 3-4 days, I started getting a few downloads, & then I noticed it WAS on the games list, getting further & further up. It wasn't until I got a few comments on the page (or maybe a rating) that the amount of downloads really shot up - so maybe comments or downloads are counted as a positive thing for the search algorithm?