This is the 3D game Ratchet and Clank 3 Up Your Arsenal on PS2. It's one of my favorite games even though I like the whole collection. Its a good game cause the graphics are amazing with how your weapon's attack explode on impact. It's funny how if you miss a platform you fall into an abyss. The levels get harder as you go further in and if your weapons not up to point you will lose. As for graphics it pales in compare to the graphics in Ratchet and Clank Tools of Destruction PS3 cause it's less cartoony and more realistic. But as it developed Ratchet and Clank I believe is to be one of the best games made with the fact that it has a long story mode.
2D GAME: http://www.youtube.com/watch?v=KcZhZ2YCppI
This is the 2D game Sonic the Hedgehog 2 on Sega Genesis. It's one of the very first games I've played and beaten as a child. As I was young graphics really don't bother and still don't as of now. But the graphics are decent for a old school sega game. But as Sonic the Hedgehog advanced the graphics did too. (Sonic the Hedgehog 2, Sonic Adventure, Sonic Heros.
My Favorite: http://www.youtube.com/watch?v=j8vyxB1oAVo
This is the 3D game Sly Cooper on PS2 and PS3. It's a game similar to Ratchet and Clank cause the graphics on par with Sly and it really caught my eye. It's not as long as Ratchet but still good. As for graphics it also evolved as it went along from Sly Cooper and the Thievius Raccoonus, Sly 2 Band of Thieves, Sly 3 Honor Among Thieves, and Sly 4 Thieves in Time.