Space Marine 2 only allows for 3-player co-op because Space Marines "are almost invincible" and any more would make the shooter "too easy"

gamesradar.com:

Saber Interactive has a good reason behind why Warhammer 40,000: Space Marine 2 is only getting three-player co-op - the Space Marines are simply way too OP.

Speaking in an interview with PC Gamer, brand and creative manager Yann François reveals just how powerful Space Marines truly are. "When you are reading about Space Marines," he explains, "Ultramarines and Primaris - you discover that they're superhuman on a really crazy scale. They measure up to [two to three] meters, they have two or three hearts functioning."

With two hearts, three lungs, and a powerhouse for a body, more than three Space Marines at a time in co-op mode wouldn't balance all that well. François says that developers actually tested out a four-person version, but it didn't work - Space Marine 2 ended up being way too easy."[It] was quite a challenge for the team to say: 'OK, [Space Marines] are almost invincible. How do we create a challenge around it?'"

François continues, detailing the "massacre" that occurred during the trialed four-player mode: "Because it could be super easy … That is what led to the choice of creating a multiplayer of up to three players. Because many people asked 'why is it not up to four players?' They tried it, and they realized it was too easy … it was a massacre. So three was a good number."

Considering the fact that Space Marines have bioengineered organs, the height of a giant, and the ability to stay awake while half their brain sleeps, I'd personally say that three-player co-op is more than fair. It's exciting to see how true to the lore Space Marine 2 is staying, too - sure, the devs could've adjusted things to allow for more players at once, but keeping the superhuman Space Marine abilities intact is the way to go.

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