It's also a little disappointing to see no form of ship upgrade system, or even multiple ship types being included in the game. (thexboxhub.com)
Money can also be used for ship upgrades such as more lasers, gun power upgrades and gun recharge which helps speed up the gap between shots. (plusxp.com)
You have to «Save the last humans» in order to unlock ship upgrades and increase your overall score. (playstationing.com)