It's way more than that..
like I said most large OPS are not only organized by active/retired military but alot of the larger OPs are hosted on Military bases all over the US.
one of The biggest being the LIONCLAWS op
http://www.oplionclaws.com/
The individual units work within the larger unit structure with all different objectives..
these ops can last for days at a time.. 24 hours in some ops where NVGs are required.
the ops can take place on 1000 acre wooded areas with over 500+ people involved.
radio setups are mandatory for almost all ops.
as are proper uniforms for your unit.
(ours since we were all dept of the navy personnel we wore MARPAT and the proper firearms ( M4s and variants/M9s SAWs) for the deployment.
OPFOR will usually dress the part depending on the op as well.
from anything like Somali like urban attire with AKs to full blown Russian or Chinese BDUs and equipment.
there are units that only do OPFOR just as mine only did US Armed Forces.
its alot of fun but very physical as well as demanding of knowing how to move in combat situations.
most people that haven't served in a combat unit don't seem to like it as much as just going lone wolf in paintball.
very expensive hobby as there is lots of travel and the equipment is expensive even if you already have most of it from serving..
my Airsoft weps alone were in excess of 2000 bucks.
Not to mention radios/Throatmikes/NVGs for night ops etc..