Let me tell you a little story about a coworker and a friend of mine. A guy who refused to buy into console gaming. A PC Master Race kinda guy. Then one fateful day, I was given a Helldivers code. His life changed in an instant. Not only was he intrigued by the challenging Helldivers gameplay, it drove him to actually purchase a PS4! Helldivers! Well, the game's on PC now, so I guess the joke's on him.
But seriously, Arrowhead Studios did something right, when their little alien twin-stick shooter could convince someone to buy a console.
Helldivers, put four players together in an effort to fend of hordes of giant alien bugs, cyborgs and squid-like creatures called the Illuminate. Much like Magica, players had to be mindful of each other and their location since friendly fire always enabled. It made tense moments where enemies would swarm from every corner of the screen that much more intense, as you had to make sure you didn't snipe your friends head off, or trample him with a giant mech.
There was also a persistent war that had players constantly pushing these alien forces away towards their home base, enabling a constant tug-of-war of sorts, as players tried to push enemies away from Earth, and toward the aliens' home planet. Each win contributed a bit toward the overall war effort.
That said, playing the game solo can be somewhat boring, so make sure you have friends that are willing to contribute to the war effort with you.