As the Gods Will (2014)

Both are set in highschool, eventhough the clue isnt a game it's set in highschool and the male lead and female lead struggle to find a clue for a murder. They have to find it in one period. This may be a good movie to watch if you like as the gods will

Both movies share more or less the same idea. Personally I liked both movies, if you like gore you will like as the Gods will

I'd say this is kinda like the adult version of Kamisama. Same atmosphere and everything.

A group of people being killed off because they lost the game. An adult version shall we say?

In As The Gods Will, students are made to play different games which involve death. Unlike in the sacrifice dilemma, they need to choose a sacrifice to save their class.
So basically,
-Death Game
-High School
-Creepy gamemaster (ig u could call it that lol)

-action genre

-they have to fight in both movies

- while watching ''Gantz'' I thought about the other movie

-have similar plot and feeling

These two flicks have the same basic theme - in order to survive - you have to play the diabolical game. However, there is a bit of a difference in the air of the movies.
While Ousama Game stays at the creepier side, following the classic concept of an Asian survival horror movie, As the Gods Will strays into the really bizarre and surreal, with much more fantasy elements. The latter is based on a highly popular horror manga and I for one, prefer AtGW due to the more complex plot and high energy development and pace.
Ousama Game isn't very graphic but As the Gods Will is quite gory.
But if you like the concept of survival games, you will probably like both.

Similar vibe. Same sorta story where young people are getting killed off.