It largely depends on the type of game. There's are plenty of games I've played where you're still in the tutorial after 2 hours. Hell, I don't think I knew if I liked EU4 until I was like 50+ hours in.

You don't need 2 hours to figure out if you like Super Meat Boy though. You'll know in less than an hour. Probably less than that.

For those who wonder how you could play a game for 50+ hours and not know if you like it; it's a grand strategy game with lots of functionally. A full game can easily be 50+ hours depending on how fast you let the game run, and your first game is definitely going to have a lot of pausing trying to figure out various functionality. First game is or two is just figuring out the basic gameplay.