Over the weekend, I realized an important aspect of suits in game design. They restrict options and therefore increase tension.
Imagine a game of Lost Cities where all of the cards were of the same suit and they could be played on any expedition. Now instead of a 20% chance of drawing the suit you need, you have a 100% chance. The discarding aspect of the game would be pretty pointless. In short, all of the interesting decisions go out the window.
This seems pretty obvious in retrospect. In fact, I’ve added suits before to games for that very reason. I guess I was just oblivious with my perpetually undone game, Venture Forth, which was lacking suits. The game gave you lots of options, but ultimately felt flat. I added suits yesterday and all of a sudden the tension in the game started to come out! Behold the power of suits!