Survival at any cost? Both movies stick to the (by now classic) theme of getting through a terrifying game in order to survive.
Battle Royale is by far the most well known of the Asian ones and the one that paved way for all that followed. BR is much gorier but also better in plot and premise. If you like survival flicks, you will probably like both of them.

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.