To remove the hud from Shank:
1. Go to this folder: Shank/data/ui
2. Find gamescreen.gfx
3. rename it to gamescreen.gfx.bak
4. Now, copy header.gfx and rename the copy of header.gfx to gamescreen.gfx
5. Run the game.
Side Effect: The cutscenes will no longer play with the hud disabled. To skip the black screen which shows instead of the cutscenes, press start and then X (if you're using a controller) or Escape and then Space if you're using a keyboard.
Note: Unlike Shank 2, Shank 1 allows you to carry multiple weapons of the same class (for example, pistols and a shotgun). To switch, you will need to use the directional pad on a controller. Up / down switches shooting weapons and left / right switches between the chainsaw and whatever other strong attack weapon you also have. If you're using a keyboard, use whatever keys you chose in the options menu.