As far as I'm aware they never explain the rules of Stratagema. I feel pretty comfortable saying it seems like a terrible esport to spectate. You've got

• Incredibly quick games (Data's first game with Kolrami ends in less than thirty seconds), so there's little to no time to appreciate whatever finer strategies are going on
• crap graphics-- style is very bland and more importantly user unfriendly--as far as I can tell there are four colors, navy/blank, some sort of territorial highlighting colors (blue and yellow), and a red that appears to be units/agents of both players, which are not visually distinct except for small markers (seriously, why?).
• probably crap controls-- I get you have to move multiple things simultaneously, but you'd think they'd make something more intuitive for whatever 3-D controls this game needs. With the benefit of modern video game hindsight I think something like a mini keyboard in one hand would be a lot more believable for whatever quick selection and movements are needed by this game.

Basically, take a minimalist strategy game like Go and an RTS game and stick them together in a way that uses the strengths of neither. That's Stratagema. Don't play this game, it's dumb.

(Minor edit, after thinking this over a little it's possible the red pieces are neutral objectives. I don't think that correlates as well with the finger movements, but whatever. That'd just make Stratagema 3d Liquid War with mario kart powerups tacked on)