I'm looking forward to Scott Manley weighing in on this sim with a video. Once docking is mastered, bet SpaceX could easily add in some optional failures modes. They could probably throw the kitchen sink at everyone. But to keep it manageable and not too brutally frustrating, think in terms of a minimum fuel issue or an erratic RCS thruster, a la Gemini 8.
Although Doug and Bob have no doubt mastered these controls, it's now easier to imagine how much more precise Crew Dragon software can perform an ISS docking maneuver.