The best way to survive is to pick up a number of items in the game. You can find these in crates or by killing enemies.
To pick up items, walk over them and press shoot. Don’t forget shooting near sleeping enemies wakes them up! On screen here is an Exploder type gun upgrade and a medium health recovery item.
Gun Upgrade help make your gun (Blitz Zero) more awesome! You can hold 3 Gun Upgrades at a time. If you pick up more, the first one is discarded and so on. The effects are all applied to each other to make some interesting combos!
Check that out! Exploder + Split Shot + Scatter gun upgrades. Exploder effect explodes when the bullet collides with something or stops moving. Split shot Splits a bullet into multiple shots on creation. Scatter makes more bullets shoot out in random directions when the bullet crashes.
So when these exploding bullets crash, they shoot a whole heap of new exploding bullets everywhere! Make sure you don’t blow yourself up.
You can work out the other combinations your self. Don’t let me spoil it for you.