These three are needing a mention. Also, sorry for the crap quality, I couldn't be bothered to search for the images so I took them with my phone camera. My internet's going slow, it's not me being lazy, and the fact I've still got them.

Wolfenstein 3D is awesome, I don't find any problem with it being on the Jaguar apart from the crappy controller. Although it makes switching between weapons easier. I actually have every part that came with this. The overlay, the box, the manual, and oddly the registration card for something (I must have over 100 of those things).

V-Rally is really hard. Especially with the N64, I don't know how I used to play it. It was back when I was about 5-6 when I last played this so I should take time to get used to it again.

Quake is ULTIMATE!! I seriously think this is one of the best games I own on the N64. Again, I've got to get used to the controls. Also, the best cheat ever: QQQQ-QQQQ-QQQQ-QQQQ-QQQQQ on the password screen for goodies!
Other one's I should've metioned but couldn't find the games... yet

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GoldenEye 007 (N64, definately one of the best)
Doom (Jaguar, port is amazing)
Twisted Edge (N64)
1080 (N64)
Attack of the Mutant Penguins (Jaguar)
Heart of Darkness (PS1)
Banjo Kazooie and Banjo Tooie (N64)
Mashed: Fully Loaded (Xbox Original, one of the earliest ones)
NFS Underground (Xbox Original, one of the earliest ones)
Mortal Kombat Trilogy (N64)
Some may have been mentioned but I like them anyway.