Size 6 e3 loses (Y)
e3 and symmetrical moves (c5 e5) are losing moves even if the swap rule is disabled. Blue answers d5.
Blue threats to win via b6 reduction (or e6). The plus marked hexes show the threat space.
Blue also threats to win via c5 reduction (or e5). So Red has to play in one of the hexes that belong to the four threat spaces.
Solution to intrusion in b5,b6 or c5
Blue plays d4.
The 2 threats share no space so Blue wins.
Blue had an angle template
Solution to intrusion in c6
Blue plays c5.
The solution is very similar.