You're welcome. PE was my favourite PS1 game, it was such a shame that PE2 felt a bit lackluster in comparison. Thankfully, Squaresoft used the same engine and combat system of PE in Vagrant Story as well, that was also a hell of a game :D

Only ones I remember right now are:

Final Fantasy IV : 20 hours (that's when I replay it, don't remember what my first playthrough time was)
Final Fantasy IV: The After Years: 5:30 (fighting every random battle)

Alright I updated the list and put it in alphabetical order

READ THIS: Please only put the same game in as the list if the time is completely different then the time you have, also try to make your post the same way as I made the list, it'll save me some time thanks :)

Half Life 2 - 14 hours
Blue Dragon - 33 hours (Main Quest)
Grand Theft Auto IV - 25 hours (Main Story)
Uncharted - 7 hours (medium difficulty)
Resident Evil 5 - 14 hours
Killzone 2 - 5 hours (easy difficulty)
Valkyria Chronicles - 30 hours

Resident Evil Code: Veronica - 12 hours
Resident Evil 4 - 20 hours
Resident Evil 5 -  5-6 hours
Final Fantasy VII - 60 hours
Final Fantasy VII: Crisis Core - 20 hours
Final Fantasy VIII - 90 hours
Final Fantasy IX - 70 hours
Final Fantasy X - 156 hours
Final Fantasu X-2 - 60 hours
Pokemon GOLD - 512 hours
Elder Scrolls IV: Oblivion - 120 hours

16 hours for Majora's Mask?... that must have been the bare minimum story completion Okey... unless you are talking about your fastest times rather than an average (I would deem an average as whatever it takes you the first time through)

Average for GTA vice city 30 hours? It takes like 10 hours to complete the missions? Of course you'll play it longer because it's a great sandbox game, but still :P

resident evil code veronica 23 hours
pokemon ranger 20 hours
Pokémon Ranger Shadows of Almia 25 hours
resident evil 25 hours
resident evil 2 24 hours
resident evil 3 22 hours
kingdom hearts 65 hours
kingdopm hearts 2 60 hours
okami 50 hours
super mario galaxy 25 hours
FF X-2 45 hours
FF X 65 hours
FF IX 65 hours
FF VIII 65 hours
FF VII 70 hours

Which is why the list is a bit odd.... we can't make an average of what people say without knowing what they mean. I completed Vice City main story+missions in about 10 hours the first time... so I might have put that. The 3rd (and currently last) time I went through the story I did it in about 5-6 hours.... or I could state the number of hours I could spend on the game trying to do everything (jumps/packages etc)... which would be a different figure again.

I think the OP needs to have some sort of criteria to go by... like asking how long it took someone to complete a games main component the first time they did it.... still. Many games will still get a raw deal as some don't really have a main component, or else are not focussed on a central story.

"Kingdom Hearts - Average: 64 hours

Kingdom Hearts 2 - Average: 70 hours"

what? , i thought those games are really really short.
i beat them on hard (forgot what its name maybe hero mode?) and i didnt even pass 25 hours with all unlocks.