Prepare your battlestations; alien annihilation is on the horizon! Publisher Assemble Entertainment, in coordination with Chinese partner WhisperGames, Brazilian film company Fehorama Filmes, and developer Loomiarts, today announced the launch of a free prologue of Squadron 51 on Steam. Now featuring English voiceovers, a local co-op mode, and never-before-seen levels, bosses, and gadgets for your spaceship to defend Earth from a merciless alien invasion.