The aim of the game is very simple; SURVIVE! Try and survive for as long as you can, the longer you are alive the harder everything gets. New enemies will start spawning, different bosses will spawn, and the older enemies will start getting a little more aggressive. The twist is within the powerups and spacecrafts. There are a bunch of different powerups that can aid you when battling the enemies. Keep playing to figure out what each powerup actually does. You can unlock different spacecrafts (30 to unlock), which all have a different abilities (apart from the default one) that will enhance the powerups in different ways. You also have the ability to slow down time at will. Everything apart from the player is slowed down. This is a very useful ability but you only have a limited amount of time you can use it for so use it sparingly. Earlier versions of the game were very generic, hence the name. However, I do think the game provides some very fun and unique gameplay elements.
