Console and in-game dialogs.

[Dashers 0]

We are all used to the console idea from the Quake engine, but this is a very handy tool. For being able to make precise adjustments to your settings. A major bonus would be able to alter settings in mission building.

American McGee's Alice had, what I have to say, is one of the best console ever. When pulled up your mouse can be used to drag it around like a window, resizing it etc. With the added bonus of being semi-transparent so you can still see what's happening when it's open.

Just clicking off of the console, or some other cunning key to leave you with control of your mouse. Maybe ` (below Esc, traditional console key) to load a console with no mouse, and Shift+` to load it with mouse on the console not the game engine.