Well, I guess other may find it easy because I'm not good at shoot them up, and as I tried to read everything while playing... well, let's say I lost a lot of lives = P
Yeah, 5h is really short (2h Friday night, 3h sunday night) but on the other hand, I spend maybe half an hour on paper beforehand to put my ideas and clearly know where to go.
Plus the game is awfully simple, the positions you can go to are limited and always the same, there is no collision or anything, no sprite pool, and barely any game logic, so, the perfect kind of game to do in such a short amount of time = )
Oh, and a good decade or two programming too, that helps a lot XD