We've all experienced it. That feeling when you hear about a game and you decide, there and then, you must have it. Because you feel like it was made specifically for you, it caters to your genre tastes and desires and there's something about it that calls to you.
For example:
When I was 11, I heard about Max Payne. All I knew about it was that I was an undercover cop framed for murder and out for revenge. It sounds simple. But at age 11, that sounded like the greatest thing I'd ever heard (and it was my first M rated game). I played it, loved it, and never looked back.
After GTA IV, while a great game, I wasn't hugely interested in what happened next with the franchise. But then word came out... Grand. Theft. Auto. Heist. Game. That simple concept alone guaranteed my interest. Grand Theft Auto V is now super-high on my want list.
For Tomb Raider, since I never played the old games (well, I played TR2 when I was a kid, but I got stuck somewhere and gave up) I wasn't a fan at all. Then what I heard about the reboot was awesome... mysterious island, hints of the supernatural, fucked up cults, a bow, Batman Begins/Casino Royale-esque reboot (making it grounded)... I was like... hell yes, this was made for me. As Net_Wrecker said, Arrow + Nikita... times Lost.
The idea of this thread is when you're sold on concepts because they sound like they were tailor made for you. The ultimate quality of the game however can obviously not live up to your expectations.
For example, LA Noire. The concept sold me immediately. 1940s homicide detective in Los Angeles? Untangling a vast conspiracy? Open world? Published by Rockstar? I thought I was in heaven.
Suffice it to say, it did not live up to the dream.
Before just listing games, try to give reasons why you felt like it was made for you.