I personally think SCP 303 would be a pretty minor but creepy addition to the game.

How I imagine this SCP working in the game is that it would rarely (maybe like a 1 in 100 chance) behind a door. It will emit a loud, wheezing breathing sound when the player is close to it, giving the player a heads up that 303 is behind one of the doors nearby.

If you open the door it is behind, you will be forced to look at it and will be unable to move for about 5 seconds before it disappears and the player is free to move again.

As it would be unfair if 303 appeared at the exact moment you were escaping from another SCP, he should only appear behind door near the player when you are a decent distance away from other SCPs.

While 303 won't play a major role in the plot or anything, I think it would be a nice addition to the game.

How that can be realised in SCP CB? And also the developers are work on barotrauma i dont think about it will update SCP CB before realise of Barotrauma to STEAM