Tin Star has some of the darkest and lightest moments I’ve seen in IF.
The Infinity Series and the ZE series are basically the GoT and TWD of IF, respectively (only better!), Monsters of New Haven High gives me AHS vibes (so a creepy undertone so far, leading up to something, and exploring dark themes, all made creepier by the fact that the protagonist(s) are in high school), Vendetta: Rise of a Gangster is pretty brutal (your sister has been murdered under mysterious circumstances, you’re an ambitious gangster with little to no compunction), and in Dilemma, you can hit and run, leaving a kid to die in the road rather than risk your friend’s drugs being discovered in a subsequent car search.