I’ll plug my current favorite hidden traitor game that’s perfect with 5:
Dark Moon
It’s a very simplified version of Battlestar Galactica. The space combat is gone, there is no movement, damage is the only way to lose, and cards are replaced with dice for a Liar’s Dice kind of deal. Everyone gets to choose 1 of 2 crises drawn at the end of their turn without telling everyone else what the other one was. The group has to make the target number with die rolls, but 4 out of 6 of the facings are negative numbers and everyone rolls in secret. Everyone has to submit at least one, so a traitor sabotage attempt will be passed off as “I rolled all negatives there was nothing I could do” and you have to decide if they’re telling the truth.
I love it. It’s totally obsoleted BSG for me. Simpler, easier to teach, plays faster, and better bluffing mechanics for the traitors instead of the open card counting in BSG.
Plus you can get it off BGG market for like $15.