Yes, that's what I need to achieve, don't ask why:)
So, since this is mainly OS dependent stuff I will be using Windows or Linux (whatever is simpler)
Every second my program will: 
1. do a screenshot, analyze the board and other stuff (this I can do)
2. then move the mouse to some XY and do a left-click
that's all
My main concern is: is there any library for capturing screenshots and then left clicking somwhere on the screen?
You can try to use Selenium RC + python driver for Selenium. There are means of making browser screenshot, and there is ClickAt method which takes coordinates.
python program that plays flash games for me