The Life Foundation and four other symbiotes were the antagonists so I guess the movie drew inspiration from the same story line as that game. Main problem with the villain is that he's just a generic evil CEO that gets posessed by the symbiote leader and he doesn't transform until the third act.
One smart thing the movie did was making Venom an actual character with personality and an arc rather than a mindless evil alien like Spider-Man 3 did. It's kinda funny how he gets annoyed whenever someone refers to the symbiote as a parasite and constantly bickers with Eddie about devouring human heads. Venom in the movie isn't evil but his motivations are purely selfish and not heroic so he still fits an anti-hero role, basically he doesn't want to share Earth with any other symbiote so he turns against Riot before the latter brought the rest of the symbiotes.
The movie also worked surprisingly well without Spider-Man, the only thing his absence affects is Venom not having a tarantula symbol on his chest, other than that Spider-Manless Venom origin worked fine in my opinion.
There wasn't anything that suggested the movie was supposed to have horror, turns out that was just the trailers marketing the movie, but there were indeed scenes that were supposed to have violence and gore, which I think they should've kept.