Dio...man,he was a genius...I mean,just take a look at any of his lyrics(my greatest recommendation:Don't Talk to Strangers)
I once saw an interview where he talked about religion,and my head just exploded with how much have I agreed with him! If you're interested,it's here: https://www.youtube.com/watch?v=CLuUDrrP44k A great quantity of high quality Truth in less that two minutes!
I remember so clearly playing GTA:Vice City Stories and hearing Dio's "Holy Diver" on the V-Rock radio for the first time...Still one of the best songs I've ever heard(and I've listened to a lot)!There were so many other kickass metal songs on both Vice City Stories' and Vice City's V-Rock,such as Judas Priest's "Electric Eye" and "You've Got Another Thing Coming",Iron Maiden's "2 Minutes to Midnight",Queensryche's "Queen of the Reich",Megadeth's "Peace Sells" and Dokken's "Breaking the Chains"! You said that you really like GTA,so I'm sure you've heard at least one of these songs!
Rock on!