OK, add Team Fortress into the mix. It's a bit like Team Fortress in that you have a Heavy Weapons guy whose job is technically to tank like a boss; you have a medic who isn't supposed to tank but has skills that give energy boosts for tanking; you have a "spy" type who goes around knifing people stealthily; of course you have a sniper class; and you even have an engineer that puts down a sentry gun (which is so OP).
The game is fairly easy, or so I thought. I'm on the final mission (I think) of the first chapter (I think) and I've lost three times so far. I finally made it to the end and thought, "Yes I did it! Finally!" Then a swarm of enemies came at me and I wasn't prepared for them and got wasted hard. That said, there are some seeming imbalances. You have the option to capture command points. Sometimes you need to in order to prevent the enemy from calling in reinforcements, but usually it's just to make the battles easier. And OMG do they ever. You have three commands (so far, I think). One calls in an air strike, dealing 40+ damage to everything in a HUGE radius. Seriously OP but expensive to use. Another command is to give all your units 20% energy. When they get 100% energy they can do some major damage. A scout being able to take out two enemies with both at 80% HP, that's how OP we're talking. Grenade tossers can even hurl super grenades, although I don't like this function as much as the commandos' skill. The heavy gunner's skill can deal over 50 damage to a single enemy if you're lucky and at close enough range. The third command you can use gives a unit the ability to move again that same turn. You can use any command multiple times in a turn if you have the command points available. This is seriously broken on the scout -- use Rapid Strike to deal major damage with your SMG and move again, then knife the guy to death to end the turn with 60% energy, then use your Reactivate command on the scout to knife another guy, then Reactivate again for another Rapid Strike-Knife combo. Seriously OP. But still fun.