In a post-apocalyptic future, society is split up into classes which are only traversed by fighting battles. Points, required to rise in rank, are awarded for kills, and successful fighters may even have a chance of becoming the ultimate goal -- a citizen. Grey is one of these fighters -- on a mission to become a citizen at all cost. But when his friend and mentor is captured by the enemy, he must embark on a journey to save him, all the while discovering that the society he lives in may not be as it seems...
At the height of civilization, mankind stretched its reach from the distant corners of the globe, to outer space. Man's fate took a turn for the worse when a sudden wind swept across the Earth, causing all human beings to lose every memory they owned, and in essence, their humanity. Now, in a primal world with no rules, one man must endeavor to survive, to discover the future of humankind.
These movies both have a post apocalyptic and while the plots are completely different, both movies have a similar depressing feeling to them. They are both wasteland stories where people have become more isolated, guarded and prone to violence.
Amnesia tries to be a bit more philosophical, while Grey is more content to be an action movie. But the settings and atmosphere are similar enough that if you've seen one you should check out the other.
In a dark dystopic future, humankind is controlled by Dorothy, a sentient supercomputer who believes she is god. To help do her bidding, she created beings known as Galerians -- humans with supernatural and psychokinetic abilities that rival no other. Enter Rion, a young man who possesses the skills of the Galerians, and unwillingly holds the key to Dorothy's destruction within his mind. As enemies search to destroy him, Rion must race against the clock to find his long lost sister and save humanity, before Dorothy and the Galerians can destroy it...
When I was watching Grey, I kept thinking of Rion. They have a similar dystopian society, controlled by a mother computer. Both discover that society is not all it seems and must fight to protect what's important to them. If you like lots of fight scenes, both of these are recommended.
Since the activation of the Death Force program, mankind has virtually been wiped off the face of Jerra by brutal, flesh-eating war machines. A pocket of survivors live inside an island fortress led by Krauser, a MD (Most Dangerous) soldier. However, unlike MD Geist who lives only to fight, Krauser is motivated by his own ambitions for fame and power. The final battle between Krauser and Geist approaches, and with endless machines on their trail, there appears to be little hope left for humanity.
Post apocalyptic settings where violence has become the norm make these anime very similar in themes. Both these anime portray violent worlds where the protagonists are the deadiest fighters of all.
Grey has a better plot but it's soundtrack and animation aren't quite as good as Geist. However, Geist is really short and has very little going on in the story department.