6. Underground Fighting Tournament
We have to thank Gay Tony for this one. Introduced in the GTA IV expansion The Ballad of Gay Tony, the Underground Fighting Tournament was a side mission that allowed players to take part in...well...underground fighting, somewhat in the style of David Fincher's superb film Fight Club. So, for those who ever wondered what it would be like if GTA went all Tyler Durden, this side mission will make your day.