During the game players are given two choices to end the game their way. With one, you get the dark ending where Spidey keeps the symbiote and becomes King Venom of the Symbiotes on Earth with Symbiote Cat (Venomverse variant worthy of Black Cat) as his queen, click here to see it for yourself & watch from start to 1:56: I believe the intent is that he becomes evil from then on.
I believe that Spidey & Felicia will, for a while, become savage beasts striking at any who doesn’t bow to them, but at some point the echo of Uncle Ben will start screaming in Spidey’s head until he begins to listen to it. From that day forward the pair will begin to rampage against criminals of all varieties. They may even force the NYPD out of NYC. Additionally, I can also see him recruiting his former friends, allies, and repentant villains into his symbiote horde. At that point, the “real fun” begins.
The real fun I speak of is the amount of intimidation that even Punisher would say, “Dude, chill!” Specifically, Spidey & his Cat queen would maim, decimate, & outright obliterate all criminals until they break & run or turn the criminals into drones which attack those the lowlifes once stood next to. It is my theory that this vigilante horde may very well turn into a world swallowing benevolent swarm of protection. While all of this is going on, Spidey would be creating a whole new symbiote drone species. In RPG gaming fashion, he builds an army to aid in his crusade against crime. Perhaps, droned clones of his lieutenants to diversify the street sweepers as Symbiote Cat might facetiously call them. Through it all the motto of the symbiote horde would be “Great power, great responsibility, and great resolve.”