This is a tough question without some parameters. First, when I talk about a game’s size I’m not necessarily referring to its physical dimensions. Anything can be made pretty small. So the more practical question would be what is the minimum number of pieces needed to make a game?
The answer to that is zero pieces. Many games exist as simply a physical or verbal act. Some of these are even based on rules that are remembered instead of written. So there are no pieces at all.
But let’s say we want to sell a game with very few pieces, but more than zero, because people are hesitant to pay for nothing.
What are the fewest pieces we can make a game with where the pieces add value to the game experience that could not be achieved without them.
I want to say the answer is one. I tried making a small game a while back. I tried working with a single die and a single card. It didn’t really work out for me. Then I worked towards using a single tile. I made Flipped. Game play consisted of flipping the tile and then performing the challenge that was pointing at you. Each challenge involved using the tile to perform some dexterous feat. So the game was all about this one integral piece. Except that it needed a rules sheet to explain what all the challenges were. And since players earned points, you really needed to keep track with some coins or tokens. So 1 tile, rules, and a handful of tokens. Not the single piece game I hoped for.
There are a lot of small games out there. Many are a single card, but they also require some tokens or dice. Or the card is really just a set of rules for a game that needs no pieces.
When you add a few more cards or pieces, the world of micro games opens up. But I’m going to continue trying to make a single piece game.