There are 2 levels of difficulty : easy (2 rockets are fired at you at a time), and hard (4 rockets fire at you).
There's 75 levels for you to master, though if you manage to complete them all, you start again from the beginning, but everything will go a little bit faster. Each cycle through the 75 levels is called a "journey".
The level you're on determines the points you get for each pod you collect, the only exception to this is the even numbered levels ... these pods are green (or blue in "Blitz" mode) and are worth 75 points multiplied by the "journey" regardless of the level.
If a rocket hits you during a level, you will lose a life, except on green pod levels. On those levels, you simply get transported to the next level without losing a life. An extra life is given when you reach levels 25,50 and 75 in each "journey".
The rules for "Blitz" mode are slightly different ... you start with only one life (instead of three), and you don't get any extras. The pods on even numbered levels in this mode are coloured blue, and unlike normal mode, the rockets on those levels will also kill you.
This game has been tested on phones and tablets, and works on both types.