Caligula

The two shows have a similar feel and premise as both shows focus on a high school environment that has been artificially created. 

Both feature a locked in a school and they must find a way to get out and figure out why they were in this situation in the first place and both also had video games as well too. 

Similarities: -The same story plot that involve individuals in a game, where life and death was the name of the game. -The same cyber punk, and action genre. -The same character situation where certain individuals formed a team to increase they're chances of survival. Dissimilarities: -In one anime them individuals where trapped in a game where they're mission was to get out. While the other one the individuals were tricked into joining the game where to die is the only way out. -In one anime individual have to fight their fellow players whom also have the same capability , except that they don't die only get revamped, while the other one involves a real life and death situation.  read more 

Both share supernatural settings and were part of a bigger multimedia project and both also have a ya cast trying to figure out the events of whats going on in it as well too. 

Both being based around from notable video game series and covers similar psychological topics as well too. 

Both were being based around from notable video game series and focus on supernatural stuff and reality and fiction being blurred as time goes by too.