Call of Duty: Modern Warfare 4 (CoD MW4)'s open beta has barely been live, but players have already dug up a hidden reward that only exists during the test period: the "Litmus" camo. Unlocking it doesn't involve some secret map or hidden button — it's the most straightforward (and grindiest) method possible: rack up 1,500 kills in multiplayer.
That number is tallied across both beta weekends combined, so players don't need to hit it in a single weekend — progress carries over into the next one. With the beta wrapping up on September 1, that's the entire window players have to grind this one out.
What makes this genuinely interesting is the time-limited nature of it: the Litmus camo only exists in the beta. Once testing wraps and the full game launches, this camo simply won't be available in the final release — making it a keepsake exclusive to beta players. No amount of spending or grinding after launch will get it back.
This isn't the first time Call of Duty has pulled this move. Last summer's Call of Duty: Black Ops 7 beta ran a similar hidden reward system, letting beta players unlock exclusive content by completing specific challenges. Judging by this pattern, the dev team seems intent on making the beta more than just a bug-testing ground — it's meant to feel exclusive too, giving players extra incentive to spend time on test servers before the full launch.
It's still unclear whether the beta has other similar hidden challenges buried inside it, but given the scale of this beta, it wouldn't be surprising if there's more waiting to be discovered. Call of Duty: Modern Warfare 4 is slated for official release in October.
