Very hard question, but my two most played online games of this gen:

Fifa 2010 WC

Resistance 2

Mario Kart Wii
Mario Kart: Double Dash
Halo 3
Call of Duty: World at War
Super Tennis

Counting every game in a series added up

1. Halo

2. Romance of the Three Kingdom

3. Final Fantasy

4. Dynasty Warriors

5. Suikodens

80 hours of single player! How!?! How many times did you play the game?

about 7 times

4 to plat it(had to play another one because I switch the difficuly instead of starting a new game)

1 more time to expirirence it on my new HDTV

2 more times for the hell of it

currently on my 8th playthrough :p

Not sure if this is the correct order, but this will definitely be the top 5 most played.

1. Call of Duty 4: Modern Warfare

2. Pokemon Red/Blue/Yellow

3. Fallout 3

4. Fallout: New Vegas

5. Elder Scrolls IV: Oblivion

I also should make mention of the EA Sports NHL games. If we were talking about most played series of games that would easily be in the top 5, even though no single game from that series would even be in my top 10.

There is no way in hell i could do this and be correct. Ive played so many games over the years and many of them over and over so ill just list some I know i have played a ton.
Mario Karts-Super Marios 2D;s- Sonics- World of Warcraft-Ashersons Call-Lord of the Rings online- Megamans- FF's- Paper Marios- Random JRPG's- Tetris- top down Zelda's- and so on and so on, Until this gen there really hadnt been many games released in USA that didnt at least try. THe console game i have differently played the most would be between Super Mario Bros. and SMB3 other than that its all a toss up

1. Mario Kart 64 - I played this game for 2 hours a week, for about 7 years, and the first year I must have played 5 hours a week average. Played with family and friends, vary rarely alone. This game alone cost me about 1,000 hours, and it leads this list by far.

2. Mario Party 2 - You can actually do the match for how long you played this game by counting the total number of coins you collect. I average about 100 coins per game, and got 20,000 coins on my own accord (the cartridge itself has 40,000 coins because my sister was really into the game). This makes out about 200 hours.

3/4. Lost Planet 1 (360) and Gears of War. These were my very first two 360 games, and in 2007 there wasn't really that many new games which came out to occupy my time. I put in 150 hours into both of these games, mainly because the graphics awwed me at the time, and VS. Suit battles were fun. I got into Lost Planet first because Gears was so difficult, but I later switched when I maxed out my rank (well got the max achievement at level 50, and ten more levels).

5/6. This is a tie between Super Mario RPG and Warcraft 3. Both games took about 100 hours each from me. Super Mario RPG is about a 20 hour game, and I've roughly beaten it 5 times now. As for Warcraft 3, well 1 match is 20 minutes to an hour, and I played close to 100. Add single player, and the expansion, and yea 100 hours seems about right. I may have edged this over Super Mario, but just.

As for some other nominees Lost Odyssey, Fallout 3, Forza Motorsport 2, 3, Gran Turismo 3, Gran Theft Auto 3 and Vice City, Counter Strike: Source, Donkey Kong Country, Mario Kart Wii, Halo 3/Reach, Gears of War 2, Pikmin 1, Super Smash Bros (original/Melee), Stunt Race FX (SNES), Kirby's Dream Course, Pokemon Blue/Red, Fire Emblem: Sacred Stones, and Advance Wars 1 & 2 all stole over 50 hours of play from my life. Think there are more in this category too.

Easy

1. Heroes of Newerth
2. Monster Hunter Freedom 1
3. Monster Hunter Freedom Unite
4. Monster Hunter Tri
5. Monster Hunter Freedom 2

I like Monster Hunter :P

Let me think.

- Super Mario World (SNES)
- Super Mario Kart (SNES)
- Sim City (SNES)
- Pokémon Blue (GB)
- Sim City 4 (PC)