Re: longer or shorter than HL2 epi1
Sin Emergence was longer than HL2 episode 1, but only because you spent longer running around shooting enemies.
There was less different things to do in SiN Emergence than Half-Life 2 Episode 1.
Although the length of the game is less important than the entertainment to me. Some of my favourite games are incredibly short and were sold at full retail prices. Such as Max Payne, Call of Duty, Fahrenheit, etc.