This year is a very easy choice, only one game of 2005 made it to my top 50.
Need for Speed Most Wanted was fun as well, the open world was merely decent though. Psychonauts I didn't get far in. It was a great concept but the first time graphics actually put me off a game, sorry to say but the original Psychonauts on PS2 is ugly and made it hard to see what I was doing. Prince of Persia Two Thrones was disappointing, a big step back from Sands of Time.
Call of Duty 2 is one of the only CoD campaigns I have played as it was the first HD title I played on the 360. It was good for the HD experience, but didn't entice me into playing any more CoD games after. PGR3 was much better, one of my favorite racing series, needs a comeback! Kameo was also good at launch on the 360, loved it at the time, but don't know how well it stands up to the test of time.
Midnight Club 3 was competent, still fun, but not really any progress. Resident Evil 4 I skipped at the time and currentlyl waiting for the VR patch to drop for the remake (maybe end of the year or early next year) Fahrenheit / Indogo Prophecy was a nice return to adventure (like) gaming, however the ending was just weird. Loved the first half of the game.
God of War started in 2005. The first game was good apart from the infernal QTEs. Just for that reason (and for popularizing QTE during boss fights) it can't be my 2005 goty. QTE is such a cop out and should be left for rhythm games imo. It was necessary for Laserdisc games, no excuse today nor in 2005. It works in games like Fahrenheit and Heavy Rain, yet action games should stay clear of QTE.
F.E.A.R was good, great AI that was fun to play against. I can't really remember the story or much of the setting though, so it's just the AI that left an impact. Looking through the screenshots I made at a time, it seems to be a lot of empty office buildings.
Civilization IV was good, interesting to add religion to the game. Just another way to spread influence though, not much insight into religions of the world. It definitely wasn't a game changer, just another layer of (limited) complexity.
So easy choice: Shadow of the Colossus towers above any other releases in 2005. The game pushed the ps2 beyond its limits. Large sprawling landscapes with towering bosses to climb. Bosses that are all puzzles to solve instead of brute force and quick reflexes. Great story to back it all up and a landscape that is amazing to explore and navigate around. It's so nice to be able to explore a desolate open world that doesn't feel the need to constantly throw enemies and POI at you. Still tower climbs always felt rewarding for the views, and you could hunt for lizards and collect fruit to increase your stats. Just health and endurance, essential for the climbing mechanic which is still one of the best climbing mechanics today.
Agro (the horse) still also feels most like a real horse, the way Wander works with you and has a survival sense. (Avoiding obstacles and cliffs) Galloping around holding your sword up to see which way the next boss is by following the reflection of the sun on your sword, brilliant. Then the riveting chases on horse back for some of the bosses, shooting from horseback never felt as good again as in SotC.
SotC also has the best remake ever, standing the test of time thanks to it's grand ideas and ageless game play.