I'm prototyping a new game for a handheld touchscreen device at work. The device handles multi-touch and you can press down the whole screen like a big button to make a pushthrough event happen at that xy-location.
My idea is a game about exploring and building in a little top-down game world with little powered tools. I'm not sure whether I want this to be a puzzle game, or a sim game or what have you yet, but my basic idea is that you have all these little tools that are like little trucks. You might have a few tools that can't move or can't move on their own, like a generator perhaps, but most of your tools are like little trucks and can. If you click on one of the trucks, it starts up and it's pistons start chugging, and you can drive it around by dragging it with your finger. In addition to driving around, each tool-truck has a job it performs. Some are simple and require no further interaction to perform their job. For instance, the bulldozer pushes shit around just by you dragging it into stuff, the drill-truck bores through earth as you drag it through it.
Other trucks are slightly more complicated and require the use of two fingers. For instance, the crane requires you to move its arm around with your other finger, it then picks up and drops off thing either automatically due to context like the winch in Urban Strike and Desert Strike, or perhaps lifts with context and lowers with a finger tap.
An other possible concept is the idea that use of your tools drains power. Power is either drained by moving and using your tools or maybe just from actually doing their job. For example, maybe driving the drill around doesn't use power, but actually digging with it does. Energy could be recouped slowly over time or faster by charging at your generator/battery station. The generator could be hooked up to contructed windmills, constructed waterwheels. It could also be brought fuel to burn from your clearing jobs. When your buzzsaw truck cuts down vegetation, lumber is left over and when your drill bores through mountains it can sometimes find coal. This fuels can be picked up with your crane and loaded into your dumptruck and then brought to your generator for burning.
I'd like to see if anyone here has any other ideas for trucks or stationary tools, or just for game play mechanics in general. My basic idea is just to make this a puzzle game, but I think that if you add in the concept of little plebs who you don't directly control you could have a neat sim game wherein they build stuff based on what you do to the land around them with your tools.