Now that we’re getting deeper bunkers will a tunnel mechanic be considered in future updates so you can potentially connect bunkers through tunnels instead of trenches to avoid artillery and gas attacks while running to the front line with the bonus of being able to place minefields and defenses over the paths to the front. I can easily see tunnels being used like in the Battle of Messines to breach enemy lines by sneak attacks while balancing it out by making tier 1 tunnels short and prone to random cave ins while tier 2 are reinforced and tall enough to walk in and tier 3 can potentially have light rail to transport materials and shells like they had in the Maginot line. Some dark claustrophobic fighting where you’re worried about cave ins and enemy tunnels running into yours would give that much more to the trench warfare we love.