Japanese games(PSP and such)

Hello I have been playing the toradora psp game(in japanese) for a while and its getting kind of boring and its not too hard to play(language wise), for example I kind of want to play kingdom of paradise two. Im wondering in more ancient type japanese games ( for example this one has a setting 1000 years back) do they use weird/ uncommon grammar that they wont use today in the actual game? I probably wont understand much of it, but its something to consider if I decide to download it.