Games with the most longevity

Again, you need internet for Beatrider.

 

Download the songs prior to the flight? Last time I checked no internet connection is required for playing

 

True, although then it doesn't exactly have "unlimited replay value" on the flight

 

Long shooter: Cube (it's free), Galaxy on Fire
Long RPG: The Quest, Zenonia
Long platform adventure: Rolando, Rolando 2, Otto Matic, Assassin's Creed; Altair's Chronicles, Archibald's Adventures (very long)
Long TD: Crystal Defenders
Long racer: Erm... Well, I really don't know about that one. I never thought that racers should be long.

Go ahead, try 'em out.