Watch out for the tentacle 
The tentacle(s) boss from Half Life 1. Man, I remember how much trouble this fellow had given me. It was also cool how its Ai was programmed. It can't see you, but it can hear your sounds, so make a little noise and you're dead! I used to also love making the security guard try to fight the tentacle alone and die on the spot. XD
Half Life (c) Valve
This fan art is made by me and (c) me.
