First Kudos to those with the time and mod skills to keep this game ever more challenging and fun. I have over 2k hours in this game and just keep finding myself starting yet another game to see how I can micro-manage another island. For those with the skills how about these mods:
A level 3 Food Market that holds larger amounts and perhaps 3 items? Tie it to computing to simulate "on time" delivery and steel for the frame
A level 4 Food Market. The infamous Big Box Mart. Think Walmart, Sam's Club, Costco or JBs. Holds 6 food items. Needs computing for inventory management and "on time" delivery and again even more steel for the large warehouse feel.
Retaining Walls. Once you reach steel a level II retaining wall that holds back 10? Titanium gives level III which holds back 15 or 20?
Mori++ has already tackled my last which was the restrictions on Cable Bridges. I plan on starting a new game to check that out. Real world bridges often have pipes and other systems under the surface while vehicle and train traffic use the top.