It may not be a big difference but the source engine makes a good enough change to play this awesome game all over again

User Rating: 8.5 | Half-Life: Source PC
The source engine is quite amazing and it does not shine at all in this game. But with great lighting effects , good ragdolls and so on and for the small price of $10 or £5 this should be bought by anyone who hasn't allready played the masterpeice half life 1. All you half life 2 fans that have not played half life 1 should buy this , and if you loved half life 1 as much as i did , you might want to consider buying this to play the game all over again , even though its only a small change.