Small ads on the web are still more targeted than newspaper ads, since web ads appear on specific websites which are of interest to the user. If I visit a motorcycling forum, I should get motorcycling ads, and they can be effective even if they're small.
Very cool. Nice trick you guys did there with the lighter colored block, and the red enemy not being able to follow across the boundary. A lot of game developers I respect and whose games I've enjoyed started programming at a young age with simple tools which allowed getting their hands dirty. While javascript is a great language to do this, you might want to consider Game Maker Studio as well.