Cheers for the clarification 
I have never played any official indoor/CQB type games…… only unofficially around a few old factories and Farm sheds with a few mates/kids/family……… but I did spend many years competing in Paintball tournaments which were “outdoor” complexes, yet involved many CQB buildings and field facilities.
All I can recommend kit wise as an unofficial indoor gamer is not much more than any other game situation.
You DON’T need any of the fully loaded wannabe Special Forces bullshit Tactical Combat Systems that I just pictured above! 
Casual indoor/CQB style games only require a few simple things.
#1: Suitable main CQB style/size Gelblaster, with 3-4 spare preloaded magazines to suit.
#2: If the budget allows, a good sidearm/pistol. Semi or full Automatic, electric or GBB and only 1-2 spare magazines at the most.
#3: Safety wise, comfortable joggers/running shoes, lightweight long pants/long sleeve shirt, quality DYE type mask and a beanie.
(A beanie can be pulled down over your ears and back of your neck for really good protection from hits, which in Paintball would physically tear meat pieces off of your exposed extremities!)
#4: Lightweight vest/harness, minimal and lightweight as possible to only to carry spare mags, dump pouch, gas if required and maybe a water bottle depending upon the conditions. Simplicity, weight and comfort are the main considerations here.
#5: Gelblaster accessories……… a good quality touch pad high intensity LED Torch is a must! You will be severely disadvantaged and frustrated without one.
#6: Laser sight pointers……again, get a good quality unit and spend at least a half arsed attempt at getting it dialled close to your barrel at 10-15 meters.
#7: Glow Gels/Tracer Units.
Again, don’t skimp on quality, indoor environments can be very difficult to see where your gels are hitting.
A good quality Tracer Unit and Gels can allow you to fully control where you are aiming, even in higher light conditions indoors.
#8: Expensive EOTEC sights, Scopes, Optics blah blah blah…… save your money, rely on your Laser pointer/tracers/glow gels, keep your blaster as smooth, low profile, short and as light as possible…… there’s no time for acquiring targets or judging distances that apply in CQB/Indoor games!
You need a piece of equipment that is small, lightweight, free of any accessories that can snag/catch on your clothing or surroundings. Make them as slick/slim as possible and highly manageable in either left hand/right hand, overhead, prone, underhand or whatever operating position that you are needing to use them in.
#9: Attend a few different games/sessions and then fine tune your setup from there.
Get rid of anything that is uncomfortable, overweight, bulky, clumsy or not needed.
Add anything that you feel has let you down or could improve your game, and after a few short exercises you will get to a point where you will have everything on point 100% and be an absolute ninja!
