World of Secrets
A hard-edged, gritty RPG of espionage and covert operations, featuring a simple rule set for prompting intricately-interwoven character relationships and backstories, based on "World of Dungeons" by John Harper. Once you join the Company, of course, you never get out.
Note: This is a "beta" version of the WoS rules.
You live in a world of professional deceivers. Your closest allies are those best prepared to betray you. The GM’s job includes sowing discord and doubt between the PCs.
As the GM, you should periodically ask players leading questions about other player’s characters. If the answer suggests another PC is untrustworthy, give the answering player a bonus die. Also put a bonus die in the other PC’s suspicion pool (an ever growing stack in front of each player).