How to unlock all the maps?

[Vex_0G]

I know you can do it by getting a certain rank on mercenaries on a previous map, but is there any other way?

[T O S H I I E]

Nope, you need to play well and its done

[Co-CEO of HHM]

easiest way is in mercs. Sorry, no other way. I recommend breaking all of the time crystals on the map before you start killing enemies so you can maximize your combo potential. For your skill i recommend Power Counter. Counter-attacks give the most time back at +10 seconds. Sometimes you get a one hit kill with a counter, sometimes you don't, but even if it doesn't it'll do enough damage that you can melee right after for the kill. When fighting the zombies (not J'avo) when they have a melee weapon a counter is always a one hit kill in mercs so keep that in mind. Obviously use grenades and shotguns for groups. Snipers, shotguns, and magnums are great miniboss killers. I'd say Default Chris is a great starter character because his AR can mow down crowds, combat knife for melee, and magnum does what a magnum does lol. It's not hard to do if you have some patience.