after 1. ... e6 - is pretty much the only move which is a solid defence against "e3" so that you can use it every single time the opponent plays 1. e3. Other moves are more about catching as a surprise, because people tend to be much less prepared to them.
Not sure how to set it up as a gif, but here's a couple of games with 1.e3 with an opponent move that I didn't see here.
https://www.chess.com/variants/atomic/game/45731293/0/1
https://www.chess.com/variants/atomic/game/45698180/0/1
Really intersting
But i think the main line after nd4 is f5 no? Or c6?
Wolfram is a very strong atomic chess player, and his learning materials related to the "e3" which is important for the atomic community to understand. Hope you'll enjoy the study.