Today is a smaller mechanical idea that might be enough for a whole game, or possibly part of a game. I was inspired a little by Kashgar, the Kosmos 2013 Essen release, in which players are building caravans of people represented by cards in columns. Once you use a person in a column, they cycle to the back of the column, in a mechanism that has been coined open deckbuilding.
In my idea, cards are played in columns as well, except you are slowly building these columns by playing cards on top of each other (slightly askew so you can see the cards previously played). When you play a card you get its action and possibly the actions of some of the cards below it in the column as well. These actions would be categorised as either only occurring once (when you play the card), or every time a card is played on top of it. There might be a nice decision as to whether to play a weaker card that might get to trigger multiple times, or to play a stronger card that you only get to use once. Some cards could also trigger off cards below them (each card could have a type) – for example a card could gain the player $1 per shop in this column (or below this card in the column).
To stop players just building the largest tower and being able to constantly abuse the engine they are building, the end game scoring for the value of the towers would have to value building multiple towers. You could imagine a modified scoring mechanism to that of Ingenious, where you score points for the height of your smallest tower, and don’t score any points at all if you have fewer than 3 towers.
Of course, this mechanism could be the entire game in itself, and be a quick playing card game, or it could be the engine building heart of a much larger game – I’m not sure what would be best. As for a theme I was thinking the players could be building skyscrapers in a city, and the cards represent floors that they are adding to the skyscrapers, with different functions. Retail floors could provide money, residential floors could provide points, and office floors could provide special actions and bonuses. What would you do with this mechanism?