I play a lot of different games mostly on xbox.
Xbox 360
Assassin's Creed
Call of duty
Minecraft
Terraria
The Elder Scrolls
Rock Band
Red Dead Redmption
Borderlands
Halo obviously
PC
World of Warcraft
Star Wars the Old Republic
League of Legends
So basically a fairly wide variety of things.
Actually me and my cousin did the midnight challenge last week. We didn't use the incineration cannons because they weren't a one shot kill. We ended up assassinating all the knights in the level.
Personally though I think I find the commanders harder because of their cannons...
Gotta agree with Spectral on this one... I had the same problem. All my saved files were getting randomly deleted or corrupted, not just for Halo but for everything I played. I moved all my stuff to a new storage system and it hasn't done it since.
I personally don't like it that much. Most likely this is because I am just much more accustomed to the controllers over the mouse and keyboards though.
Personally I don't use sprint much because you can aim faster when not using it. It also makes you much louder, although anyone watching their radar should know you're there anyways.