Ok I'll try to explain thig.
You gain exp in this game, and the battles are huge. The way chaos is organized is by your leader giving you objectives. You level up by buying perk like equipment (raise+heal syringe/spray, gun attachments, guns, stealth, run speed, stamina, hp, explosives, claymores, the ability to control yourself more when you're falling with a parachute, etc.), the equipment you buy is yours to use with the only limit is based on the weight. You keep everything, you never lose it unless you respec.
Respec and you.
Respec is basically taking all of your skill points that you spent on abilities and equipment. Think of merit points, when you respec merit point stuff you lose all the points you spent (lolSE rite), but in mag you get every point back. The only thing stopping you from respec abuse is each time you respec the price to respec increase. What do you spend to respec? Respec points. For each exp you gain a respec point. The first respec point is 2k, the second is 7k, the third is 10k. To get to level 22 it took me around 10k I think.
Random fact:
You can shoot and kill people while they are parachuting out of their carrier plane.
Edit: Oh also, this is very important. You get the best exp from doing what you are told. If the leader give a new objective to destroy a tank you just need to be around it when it's destroyed, not 3 miles away from it. So if you don't have a loadout with rpgs just support and watch the back of people who do. Kill engineers that may be trying to repair the tank, and work as a team to get the job done. This system keeps the chaos under very good control. When people found out they got more exp from working together than they do by getting 40 kills things got very awesome.
I call Domination a 200 player HNM fight. You're basically taking down defense, and striking the heart of the enemy's core. You're met with resistance every step of the way. It feels like a tug of war situation, you have to keep pushing the line forward. As you get rid of things like AA, and their mortars you can call in choppers to drop off more soldiers (pushing the spawn point up), and fly by carrier planes to drop off around 20 parachuting solders.
http://www.youtube.com/watch?v=zmwziJeHDoo