You don't have to if you don't want to. There are hardly any reasons to play the game other than if you have no other games, or if you are forced into playing it. The game is not the kind of thing you could spend 10 hours non-stop in, as it is not addicting.

The game is simple. You avoid asteroids and collect quazars. That's about it. Later in the game, the asteroids get faster, and that's about how much different the game gets.

They added upgrades so you feel like you're progressing. You do not really need to upgrade, so far as I can tell.

They are extra missions.