From what I've shown people of the game, the things that draw attention tend to be:
- that there aren't artificial APM sinks. When I show people how a "marine split" works in ZK people get excited. Like they've never thought about it being something that should be easy.
- when I show them just how big a clusterfuck can be
- when I show them that there is no tech tree (tends to be a curiosity response)
- functional terraform
- game starts immediately, can be fighting within 30 secs on most maps
- the sheer potential for flashy creative plays
Things that tend to slow down the listener if not well explained:
- commanders being present but not being strider class
- retreat micro and bullet physics (I personally like how it works, but it's not exciting sounding)
- graphics
- modular design of composition
I think the main draw is the flashy plays though. If you could adequately communicate that during a tournament final a player impulsively gravity gunned a crawling bomb, then delivered it straight back to the center of the opponents army (which has the advantage of avoiding targeting), I think you'll have them frothing from every orifice.