3) Ratchet & Clank. I haven't played any of the games after Deadlocked but out of the PS2 era entries, Up Your Arsenal was my favorite. I spent months trying to 100% the game when I was a kid but never managed to due to my PS2 eventually bricking.

4) Sonic the Hedgehog. I really enjoy the classic games in the series, I don't mind some of the newer ones either. But I think 3 will always have a special place in my heart as I spent hours on the computer playing it as a kid.