GameTip:
 (This only if you have the (game of the year) version
 This insint exactley a cheat [you have to have the retail 
 verson disc for this to work] music like in the retail version
  
 First put in the disc, if the auto menu comes up, close it 
 go into half-life and start a new game .[the difficuilty 
 dosn't matter] once it starts up music like in the 
 retail version.
 
 Undead scientist:
 Under the dome building where you go down a manhole to the 
 sewer (because the entrance was blown up), is a man in the 
 corner who is not dead. Shoot him twice when you are talking, 
 and he should stand up and run. That is all he can do.
  
 Running from the monster alien: 
 When you are right at the end of the demo, get to the right 
 side of the platform and keep running against the edge. 
 When the monster approaches to you, he will hit a computer 
 and it causes the platform fall. Keep running to get past all 
 the debris. You will be able to run around for a short time