I guess it depends on the way the game is presented. Is it tile-based or more precision-movement based? Also, you likely wouldn't have to move the hero upwards at all, you'd just move everything downwards, but you probably already have that in mind anyway.

If it's a tile-based version, you can always just toss a line of impassable, transparent tiles one line from the bottom of the screen and go from there. (Or a tileset with the same tile as the background, but impassable)