Hipsters know what's 'hip', 'trendy', 'radical' (they'd avoid that word). How they do this depends on your level of skepticism towards the hipster. They are either attuned to the cosmic waves of human awareness, surfers of the collective consciousness, simultaneously drawn to the same games at the same time, or they read the same websites.
Flappy Bird didn't break the App Store. EA's Dungeon Keeper isn't an anti-game. And the people who play(ed) them aren't doing so against their will, or in contravention of natural justice, or in a sort of mindless stupor.