It's team-based RTS, yeah.
Each player chooses an area - Infanty, Armour (tanks), Aircraft or Support (anti-air, artillery, repair). They each have strengths and weaknesses though, so you need to overlap abilities if you want to survive.
So for example, one type of helicopter will be awesome against air units but very vulnerable from ground attacks, etc. Likewise, tanks will decimate ground units, but can be splattered by air attacks.
I only played the multiplayer component though, so I'm not sure what the single-player is all about.