Games are made up of "building blocks"

In a sense a game is a set of building blocks (or tinkertoys or whatever) put together in various ways. Some blocks are standardized (at least, from your personal point of view, stuff you've used before). But every once in a while you come up with a new block, different color, shape, connectivity, etc., or you find a new way to connect blocks.

So an experienced designer may be putting together known blocks in different ways, and maybe (or maybe not) adding something completely new.

Think of all the things that can be made with standard blocks. Lego? Click the article title for a photo of the Space Battleship Yamato, from the anime, made out of legos...

This idea of building blocks is a common one, and some people like to try to categorize the blocks used by a particular designer.

I see games as using both building blocks and systems. I do have several systems I use (Britannia is the obvious one), and there are building blocks I use often (such as Action Cards for "committed intent", either one card at a time or 4-6 at once per round). If it works, why not use it again? There's almost nothing completely original in games, but the combinations, the execution, create the unusual game.