Before you unlock anything you play on an alien moon as Spaceman Sam. To stay alive you must avoid and shoot the enemies. You will come across aliens, UFOs, meteorites, robots, space monkeys and zombie pirate cyborgs. Unlike many other endless runners you have another threat which may end the game for you. As well as enemies and timing your jump wrong you are only given a limited amount of air. The air runs out automatically, but if you get hit you will loose it much quicker. Luckily there are power ups which might protect you, slow you down or give you some extra air, your tank of air is displayed at the top corner of your screen.
The controls are very easy to use as there is only two buttons. The one on the left allows you to jump and the one on the right lets you shoot. Tapping the jump button twice will make you double jump. You can swap the buttons around as well.
Overall this is a great game and it is very addictive. I can't wait for more updates and hopefully there will be an iPad version. It is Game Center enabled and was recentley updated with colour coordinated leaderboards!