Particles on horizontal/vertical paths

Hi all,
for a game in VR I am setting a particle system for some player’s interaction with a wall. Basically, when the player touches the wall, a ribbon particle system is spawned so in that point there will be little light beams running through the wall. I could successfully get them to go only on two axis, so they don’t come out from the wall, now I’d like them to follow only vertical and horizontal paths, and not to go also in diagonal lines, like in the picture. Do someone now if that is possible?


(not the best thing but I hope it can give the idea)