The reason:
I write a lot of code with use of such symbols as
(){}",#$%$^$&<>

and i have to use shift all the time.

The problem:
After a while my hands feel some discomfort especially my tiny finger which i use to press shift.

So i was thinking if i can remap shift to space it could be a lot better. I know there is a lot of software that can do simple remap but then i have to press shift when i need to put a space. Doesn’t make any sense.

What i am looking:
I way to make work space button like this:
If i just press down then immediately release space button it acts as usual space (ie. reacts on key up event)
but if i hold it and press another keys it acts as a shift button.

Does anyone know if it is even possible to do?

You won’t be able to do that with just ST2 because you don’t have access to key down and key up callbacks; however, if you’re using OSX, you can use keyremap4macbook or maybe even keyboard maestro. I’m sure there’s something similar for the other OSs, too.