Respond with despair and intermittent rewards: When a player character sets out to achieve something, they are acting out of hope. Hope that what they want to happen in the fiction will happen. This is where you barf forth The City all over their hope. Give them what they want but twist it so that it becomes something darker and definitely not the result they really wanted. This is a great time to introduce the shifted, dark places, the shift and other generally unpleasant stuff that The City has to offer.Example.Wilbur Shivers, lostfinder of follygate project puts the word out on the streets that he wants to speak to a certain Flintwich Humbolt, a notorious local pedarast, over the disappearance of a number of children in the burgh. The MC decides now is a great time to mess with the player's head. No roll is required, instead the MC says... Three days later, three hagar enter Wilbur’s garret, a silent simil in tow. The hagar turn towards the simil, and it lifts it’s head and Flintwich’s terrified face, newly transplanted atop a simil’s wheezing and clanking mechanical body meets Wilbur’s. “Help me” he whispers imploringly. “Payment”, the hagar rasp in unison. However, don’t overuse this. Occasionally give the character exactly what the player wanted, maybe even a bit more. Play with the players’ minds such that they will want to keep trying out of the belief that this time they will get what they actually want. How often do you make the ratio between despair and hope? You know your group best, just don’t make it predictable.