Free accessibility tool.
With this tool you can create overlay buttons and define how these react when they are clicked or touched. Make them push or hold a certain key, etc. The overlays can have transparency from 0 to 100 percent. You can define exactly, what application the overlays will be available in. You can choose if the overlay fits the desktop or the application's window.
To make this happen it is necessary that the application in question runs in windowed mode.
With Alt-Controller it becomes possible to to play racing games, Jump'n' Runs and many WASD titles with only the movement of the mouse.
And there is more to Alt-Controller! You can even create GUIs with buttons in different colors.