The whole thing of Perfect Dark Zero done on the Dark Agent difficulty. Need help on figuring out what to do or just curious to see how the story goes? Watch these.

Mission 0 - Datacore Demolition
http://www.youtube.com/watch?v=CgS2UquNlBg
http://www.youtube.com/watch?v=wCuP8UOZxSA

Mission 1 - Nightclub Stakeout
http://www.youtube.com/watch?v=AmAgTxSCqxw
http://www.youtube.com/watch?v=EQQIG_Br37w

Mission 2 - Subway Retrieval
http://www.youtube.com/watch?v=4Ml91RNH7RM
http://www.youtube.com/watch?v=kUEWqz7YiEc

Mission 3 - Rooftops Escape
http://www.youtube.com/watch?v=iMSEpdVOhqs
http://www.youtube.com/watch?v=R_cw9A32CCI

Mission 4 - Mansion Infiltration
http://www.youtube.com/watch?v=HF40hNoMqoc
http://www.youtube.com/watch?v=GTNsU4-ZtlQ

Mission 5 - Laboratory Rescue
http://www.youtube.com/watch?v=ADJJuxiHhdI
http://www.youtube.com/watch?v=oKq2x3VmVBo

Mission 6 - River Extraction
http://www.youtube.com/watch?v=qdRDDuS5Fns
http://www.youtube.com/watch?v=fjewvp8hdJk

Mission 7 - Trinity Infiltration
http://www.youtube.com/watch?v=ZlJG_YwY8Jo
http://www.youtube.com/watch?v=XQolgQssBio

Mission 8 - Trinity Escape
http://www.youtube.com/watch?v=OUPBJobTMC8
http://www.youtube.com/watch?v=FHdFDdldKYs

Mission 9 - Jungle Storm
http://www.youtube.com/watch?v=eLd5dlQYSAk
http://www.youtube.com/watch?v=hayD6mlpp1Q

Mission 10 - Temple Surveillance
http://www.youtube.com/watch?v=zoXTQm0zFCw

Mission 11 - Outpost Rescue
http://www.youtube.com/watch?v=UKt1YXbE7tE
http://www.youtube.com/watch?v=hofPhj89nvY
http://www.youtube.com/watch?v=wB_V1XXob6g

Mission 12 - Bridge Assault
http://www.youtube.com/watch?v=cAnw1sXRd_8
http://www.youtube.com/watch?v=fAjSZu_CrJ8
http://www.youtube.com/watch?v=UhmS5y-PAag

Mission 13 - Arena Showdown
http://www.youtube.com/watch?v=5Mo8ePiGzRc