That Earth Defense Force 5 will be coming over to the west, is something that D3 Publisher actually announced all the way back in April. It was a bit of a empty announcement, though, since it didn’t share any information or details at all back then.
D3 Publisher finally broke their silence with a brand new trailer for the localized version of the game- but this trailer, while giving us some footage of the game to chew on, still doesn’t share a release date, or even a release window, for that matter, for the game- all we get is a vague “coming soon”. Since the channel has been shared on the official PlayStation channel, we can also now conclude the game will actually be coming to the west on PS4- but that obviously doesn’t mean that it’s not coming to anything else. It still could- it’s just that Sony have no reason to advertise a potential Xbox version, for example.
Earth Defense Force 5 launched last year in Japan. It will come out in the west eventually, at least on the PS4. We know that much now, if nothing else.
