The universe is in need of a great hero to save it.
The story begins with Vilgax and his army starting a attack on Bellwood as Ben along with his cousin Gwen and old enemy Kevin are trying to stop it but then they discover that Vilgax is planning on using a Null Void machine so he can trap the planet Earth within it in the hopes of finally defeating Ben but hope is not lost as Professor Paradox shows up to tell the kids that this event can be stopped if they go back in time and try to destroy the energy sources that are needed to power up the machine so the race to save Earth and the whole universe rest on Ben's shoulders.
There are eight different levels to revisit within this game as you must get through them in order to get to the power source that you need to destroy but like always it's not that easy as there are always enemies to battle as when you defeat them you can count points that can be used to upgrade one of your alien forms as you will need them as the bosses in the game will look familar as alot of them are bad guys that appear in the Alien Force series plus you can meet enemies that Ben once battled in the older series which was cool as I liked the old series plus when you are exploring the areas be sure to keep a eye out for special items that can increase Ben's health and energy so he can stay in his chose alien force for a longer time.
What is really great about this game is unlike the other games on the Playstation 2 which only had you play as 5 aliens in this game you get to play as all 10 different aliens as they Swampfire , Spidermonkey , Echo Echo , Jet Ray , Big Chill , Chromastone , Goop , Humongousaur , Cannonbolt and Brainstorm but I should mention that after the events in the first level you will only have the power to use from a few of them since Ben used alot of power in the beginning saving the city but on the other hand each alien has it's only special powers that are useful when going through the levels like Goop can bounce from wall to the other to get to higher locations , Big Chill can glide across areas that are too far to jump and Brainstorm can hack into computers to only gates but the rest you will have to discover on your own.
I have played the other games based on the Ben 10 series but I enjoyed playing this one so if your a fan of the series or even if have played the other games then be use to give this one a try.