Sinister City is a hidden object game with standard features of classic point-and-click adventure titles. Most of the time, the objective is to find and collect a series of items scattered around certain locations. Pictures of the objects appear at the top-left corner after talking with other characters or advancing the plot in some other way. The player has to move between connected rooms and click on certain areas to access the separate screens where the items are stored.
Once all the instances of the objects are found, they are added to the inventory tab at the bottom, from where they can be dragged and dropped on interactive portions of the scenery to perform an action or solve a puzzle. The hint button is a large ? at the bottom-left corner, that shows the position of one of the required items when activated, but takes some time to recharge after use.
Mini-games take place on separate screens, where pieces and mechanisms have to be manipulated directly to solve puzzles, like connecting pairs of twisted wires by color, assembling clockwork pieces, restoring the shards to a broken mirror, moving horizontal bands to complete a sketch portrait of the Count, placing vampire hunting tools in pockets with their silhouettes, connecting a series of gears and completing other similar challenges. They can be optionally skipped after a few minutes.