Just don't watch this at all
I see lots of people asking if they should watch Cube Zero before or after the other 2 Cube movies, and I just have to say: Do yourself and favor and forget there is even is a Cube Zero. I kid you not, this movie is GARBAGE.
If you watch it first, them you may not ever get to Cube 1 and Cube 2, which would be a shame, as Cube 1 and Cube 2 are great and good (in that order).
If you watch Cube 1 and Cube 2 first, then Cube Zero will do nothing but ruin those films, because the junk they made up to explain all away is SO HORRENDOUS. I mean, like worse than SyFy Channel level of bad. Worse than giant CGI snakes eating people bad. Just. Plain. BAD.
Undoubtedly, someone one day is going to reply to this and tell everyone that its not so bad and blah blah blah. No. I am warning you now. Watching Cube Zero, next to Cube 1 and Cube 2 would be like being served a plate with lobster, steak, and a side of rotting fecal covered rat carcass pulled from a Port-o-potty used at a 3 day music festival in the desert.