You can count on summer for two things: horribly inhumane temperatures and the Steam Summer Sale. When the Summer Sale comes 'round every year, Steam slashes prices on hundreds of PC games. This year's sale includes steep discounts on  games like Starship Troopers: Extinction, Sea of Thieves 2023 Edition, Monster Hunter Rise, and many more. To make things easier for cooperatively-minded gamers, we've assembled this list of co-op highlights from the sale.