PlayStation 3

Final Fantasy XII [PS2]
Persona 4 [PS2]
[open slot] <-- haven't thought of yet


The other "runner up" games in order:
Monster Rancher 2 [PS]
Pokemon Yellow/Blue/Red/Green [All the same except for slight difference in Yellow]
[Gameboy Color]
Final Fantasy IX [PS]
Resident Evil 4 [PS2]
Residen Evil 5 [PC]
Catherine [PS3]

Assuming there will be a continuation of new content from online enabled games:
Halo (4). Between campaign, forge and mp there is new content, maps and game types to last forever.
LBP 2. Not one of my favorite games but one I would envision would still entertain me 5-10 years from now
Skyrim. Though this would undoubtedly grow old eventually, it would retain its amazing appeal for a very long time. I've put more time into it then any other non-mp game in the last 10 years and am still scratching the surface
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"I'm not scared...I'm singing. My screaming song."
"You're a total wuss."

Natural Selection 2
Rift
Smite


Yes, they are all for PC because I don't think I could play any PS3 game for the rest of my life.
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90% of my posts end a topic, every time.
http://i.imgur.com/3m3G1.jpg

Dark/Demons Souls
Final Fantasy IX
Little Big Planet 2

If there was other people to play with me then it would be more like this:

Worms
Smash Bros Brawl
Little Big Planet 2 or Tekken 5 DR
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Ruler of the FF Agito XIII Boards 2011-2012
The Official Creator of the Noctis Orgy on the FF Versus XIII Boards

The Legend of Zelda Twilight Princess (or any TLOZ)
Super Smash Bros. Brawl
Fallout 3
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I_|||||__/'''''''''[{]''''''''{_Pwned_}'''''''''''''''''''''''''''''''''' Would you Kindly?