I really like this game but lack of strafing with A and D keys just gets on my nerves. I`ve heard that there was a mod that fixes this issue and adds a key for running (that double tap function seems awkward too). I can`t really find it anywhere. Does it still exist, and does it work with GOG version ?

You could search for it over here, even if a quick search did not prove sucessful. However, it is a good place to start IMHO.

I`ve found something here

http://blade-of-darkness.bigtruck-canada.ca/mods/mods.htm

It`s called respawn-strafe. I`m not sure if it will work with GOG version. Here goes nothing......

EDIT: It works but not as I intended. I can`t move diagonally (forward and strafe at the same time) and my character doesn`t take damage when hit by enemies :(

I think I`ll be going back to my old configuration unless someone knows how to turn off god mode.

EDIT EDIT: The god mode only works for previously saved game. When I start a new game it goes back to normal but this strafe is a little shabby unfortunately :(

If anyone got here after the rerelease only to find a dead link, it is archived on the Wayback Machine
[url=https://web.archive.org/web/20200604170749/http://blade-of-darkness.bigtruck-canada.ca:80/mods/mods.htm]https://web.archive.org/web/20200604170749/http://blade-of-darkness.bigtruck-canada.ca:80/mods/mods.htm[/url]
I haven't tested the mod with the new version yet, though.