FYI regarding mechanics...
What that means is that for a start you can look up and down, you can lean around corners -- you currently can't shoot but also won't be seen. You can sneak up behind enemies and perform sneak attacks -- you must be crouched and using a knife or silenced weapon.
My plan is to make it more of a stealth immersive sim. So far sound affects your ability to be detected, working on shadows -- you can actually shoot out most of the lights in the game. Still need to fix the AI so that it doesn't spot you as quick by sight.
There are several enemies in the game, you also can make use of several weapons: knife, silenced pistol, pistol, submachine gun, silenced submachine gun -- these you must find. I plan to add more in the future.
FYI there are several secret areas where you must interact with the wall to gain access -- this is a bit less trial and error as compared to Wolfenstein 3D; TIP there is one nearby where you start.
When you reach the end elevator, you can consider the demo "finished".