First, let's define what I mean by the mid-game. Many people would probably define it slightly differently but I think that most will agree that if you have this check list filled out you are very definitely in the mid-game. - Permanent solution for base cooling - Permanent solution for higher tier food - Permanent solution for oxygen - Stable power supply - Stable water supply - All pre-space research done - All dupes have access to atmo-suits - At least temporary production