Hello there, First of, I love this game. It reminds me so much of Space Colony and Outpost. And both are fond childhood games of mine.
But I do have a few suggestions for area's I felt could use fleshing out or improving.
Commute: Commute right now is handled by walking through tunnels. As a colony grows larger the issue gets worse. If you're building in area's where space is a luxury, the issue is made worse. Logically the fact the workers can travel directly from building to building would be a boon to commute, rather than needing to traverse a tunnel. But as colonies grow larger I've noticed the AI dosn't relocate workers to live in places closer to their work place. Thats why I thought it may be beneficial to provide some sort of transportation system. Either by using production lines to make Segways and "Hoverboards". Or by building Monorails, VTOL Buses or Trains.
Air: I don't know if this is intentional but I've noticed that even with a lot of Purifiers or Intakes the quality of air can still be a little low at times. This could be a bug, but I thought it may be better to have a high end, final tier building that either converts the atmosphere and distributes it across the whole colony, or by having Parks contribute to Oxygen levels. I'd say have a end game project to terraform the planet but given the effort to make the colony so hermetically sealed and designed, I doubt that would be a design goal for the game.
Security: Sometimes it's not financially viable to have plenty of drones of this type. But I figured it may be a good idea to have a policy for Community Policing/Community Watch. This would benefit early colonies that can't dedicate immediate resources to security via drones and drugs.
Population: I've noticed rather interestingly that the only way to get workers is to bring them in. I'm surprised since they are humans. Humans will form bonds, fall in love. Reproduce. It's why I'm surprised there's no School buildings. Educated workers would carry an Efficiency Bonus for working on the planet.
Food: Simply put, Live Stock. Humans aren't biologically designed to survive on a Vegetarian diet. Unless in the future we have some super plant that contains all the calories, protein and minerals of meat.