PacMan does not require a designer to carefully craft a puzzle mechanic. Instead, the rules and resources of the game are enforced by the some-what AI controlled ghosts. The fun of it comes from working out the escape routes that are thrust upon you by the game. Neither does Tetris. Compare that to a game like monkey island where 100% of the challenge came from a trap that the designer specifically laid out for you. It is obvious, but I realize, now, how such a seemingly minor difference in game style can have such a dramatic impact on how the game is created.
City Tuesday is a game that falls under the “designer-intensive content.” And it is really hard. I am not saying it is more difficult than making a really great shooter but I am saying that making content for a game with puzzles requires more attention from the designer in order to get a basic interaction. I can make one screen a neat puzzle only to blow it with a blah puzzle in the next screen. Also, with a shooter, a designer can play it and know whether it is fun or not. But you can’t play your own puzzles. It is like trying to tickle yourself.
If this is your first game, I would recommend not have any puzzle mechanics. I created this handy spectrum of games from almost self-perpetuating fun in Minecraft to the heavily designed fun of Monkey Island. Note that games like Halo and Uncharted fall in the middle because they do have a fun shooting mechanic that would sustain itself if you just threw the player in a room full of guys. However, the variations and the long-term interest requires a designer to create missions and harder arrangements of enemies and bullets.