I really like the idea, and the page design adds a lot to the experience right out of the gate. I found the difficulty level really high, it felt like I was just learning how to move and aim, and then earth was already eaten. Some sort of game over or win mechanic would be awesome too, I really wanted to save the earth after reading the epic backstory and mission data!
The art and sounds made it feel like one of the old DOS arcade games from the early 90's. I love the look and feel. It would be really cool to see some of the story on the page put into the game, with maybe a training mission and some simple pixel VFX - Obviously too much for the jam time, but maybe a future build?