#5 - Pokemon (Heart)Gold / (Soul)Silver (Gameboy Colour / Nintendo DS)
*phew*
This game was my childhood. You would not believe the amount of cheap AA batteries I used up playing this game over the years.
Although this was my first Pokemon game, and I'm probably looking at it through rose-tinted glasses, I do believe that this is the definitive Pokemon game. It had not only Johto, which I consider to be the best region, but you also got to re-visit Kanto and practically play Pokemon Blue / Red again! Each town in Johto was distinctive and memorable, and crossing the ocean for the first time absolutely blew my mind. This game had the iconic original 150 Pokemon as well as 100 new welcome additions, which I feel is just the right amount. I also thought the new legendary Pokemon were great, and chasing the legendary dogs was a fun challenge. Pokemon breeding was added, which was a very useful and entertaining game mechanic. One of the best things about this game though is its difficulty. All of the other Pokemon games I've played seem like push overs in comparison, but in certain areas this game put up a real fight, and being "whited out" was pretty common.