AutoFire is a mouse clicker designed for Chicken Invaders but works with many other games.
The goal behind Autofire was automatic firing with low overheat, and no code injection, to avoid games crashing.
AutoFire is portable so merely start the app and leave the window open. Press left ctrl to start or stop. The left shift key can shift from low overheat to no overheat modes. These modes can be customized on the firing modes tab. You can set different mouse click speeds in milliseconds. Optionally, you can also run these as command-line arguments.
As mentioned, while initially designed for Chicken Invaders, it might work with other games and application, though your mileage may vary.