This generation has seen the rise of the co-op third person shooter thanks to games like Gears of War and Resident Evil 5. Players can team up with their friends online or in the same room and go through the entire game’s story. Army of Two was a game made specifically around the idea of two-player co-op campaigns.
While the game played fine by itself in single player it had a few mechanics that worked great with two players, and made the game stand out. Things like one player holding the shield while the other gets behind and lays down cover fire, or where one player boosts the other over a ledge and the other clears the platform, or go back to back to fire in 360 degrees. The key mechanic for two players was the Aggro mechanic which allowed for flanking opportunities not present in other co-op games.
The way the Aggro mechanic worked was as a balance between players and their aggression toward enemies. If both players were continuously firing at them, both would be equally targeted by the enemy AI. With the Aggro system, one of them could do all the firing and draw all enemy attention towards them while the other laid low. What happened when this maxed out was the aggressive player would essentially turn Super Saiyan by doing extra damage and never having to reload. Also he turns red. It’s pretty sweet. As for the non-aggressor, they become invisible and move faster so that they can melee enemies easily.
Like all good PR videos, Army of Two has one to explain this with some casual-serious dialogue:
Of course, the system was a bit more advanced than that. Due to one of the two drawing all the fire, it was entirely possible that he would be shot repeatedly and come close to death. Hence the Feign Death mechanic. If the Aggro player was about to bite the bullet (or, well, one too many), they could feign death and instantly transfer the Aggro built to the other player so that they could keep the meter going. Even if the other couldn’t go all Solid Snake around the place, the Super Saiyan player would have enough of an advantage themselves.
Another advantage of this Aggro system was that it effectively eliminated the trench warfare aspect of cover-based third person shooters where the player and the enemy would hide behind the respective pieces of cover and fire in the other’s general direction until one of you dies. Here, one person attracted all the attention while the other one could move up and take them by surprise. And it didn’t just work with single enemies, it could work with entire groups. Again, something else sorely missing from most third person shooters.
It’s a bit strange that Army of Two is the only game that really adopted a system anything like this. While not every game needs one quite as over the top as Army of Two’s, a simplified version that has the enemies focus firing on the more visible player would add a lot of tactility to any co-op third person shooter. Instead, the enemies split their attention between players evenly, even when one has been hiding the entire time. While it’s commendable that this unjustly forgotten series thought to have anything like this, it’s really a question for the rest of the genre as to why their AI exists as nothing more than psychic Stormtroopers for the protagonists.