Every map has one feature that is unique to it only or something it introduced and was then included in other maps. Ascent has breakable doors. Bind has teleports. Haven has 3 bomb sites. Split introduced zipline and water. Breeze brought unbreakable doors. Fracture has 2 T spawns and automatic door. What did icebox introduce? Is there anything? I can't recall.

Edit: I forgot to add the most obvious one. Fracture's ziplines are one way.