ZCOIN is the name of the virtual currency used in Blacklight: Retribution that allows players to buy in-game items with real-world money.
ZCOIN compared to GPEdit
GP (Game Points), which are awarded for playing matches, can be used to buy most items. However, you must meet the level requirement for the item you want to buy.
If you purchase an item with ZCOIN, this minimum level will not apply, and you can immediately use the item regardless of your level. All basic weapon types are permanently buyable with GP, provided you have Blacklight Prime. So while a player using ZCOIN can cut short the time until he owns a specific item, a player who relies on GP is not excluded from owning it, too.
However, there are some items that can only be purchased with ZCOIN, like camos, Reward Helmets (indirectly through chance packs) or Heroes. Most of the items that can only be bought with ZCOIN would classify as a 'cosmetic improvement' and won't allow a player to become overpowered.
Buying ZCOIN Edit
ZCOIN can be bought using real-world money at the ARC website. It follows the rate of 1 US dollar for every 100 ZCOINs, starting at a mininum price of 5 dollars. After buying, the player must go to the ZEN Transfer page and transfer the bought ZEN to their Blacklight account.