SCP-500 wrote:If the player hides before the MTF can see him it would work.

If I was an MTF sent to check on The Possessive Mask during a containment breach, then my first instinct would be to check the control room, especially given the fact I'd know about the haemorrhaging problems created when exposed to the containment chamber itself where the scientist is.

Perhaps SCP 035 can be seen walking in unreachable areas like a catwalk

Personally I think that scp-035 should be found shot dead at gate a is anyone with me