This is the heart of Xcom: Enemy Unknown. Your underground base. There are a variety of facilities, including a science laboratory where you conduct research, dissections, interrogations and other extraterrestial interactions.
The Engineering bay. Here is where you construct all the practical science-born conduits and inventions for both your soldiers and the rest of the world to use. It takes both money, material, manpower and the know-how in order to do so.
Another, less important section is the Barracks. Here is where your soldiers are kept and maintained. You also recruit new ones from here but hopefully, you will not have a need to do so as every soldier is invaluable. Especially your experienced ones.
You can see the status of all of them at any time, along with customizing their apperances and loadouts. More on that later.
Another thing worthy of mention is the officer training school. Here you can unlock special traits for all soldier's benefit, including speed-up recovery times and much less fatalities if medkits are available. Don't worry about it now though, as they all require sophisticated research and high-ranking soldiers.
This is the facility building overview menu. Here you can see what space is available for construction and what can become available through excavation. Very careful planning is required here or catastrophy will soon follow in form of low efficiency and sky-high maintenance costs as the further down you go, the more expensive things become.
I recommend starting excavations and building access lifts at least down to floor 3 to be made as soon as possible to avoid any dilly-dallying by the engineering team. Don't build anything right now as we lack both manpower, research and money.
While half-a-dozen of materials and research projects will be available to you through-out the game, utlizing common sense will often get you what you want. For example, my priority is to make you survive this game. And for that, we'll need to make sure our soldiers don't die off left and right.
For that, they need armor. For armor, you need stronger materials. And thus, you research these recovered alien materials.
Once researched, items and other materials will be available here in the engineering bay.
Right now though, you only have access to medkits and satellites. Medkits are really sub-par at the beginning because they take up an item slot which you currently have free grenades in. Satellites will always be in-demand as they can be used to not only monitor regions for alien activity but also because they generate gigantic amounts of extra money when deployed to certain nations.
When done with everything you can do at a moment, you click "Mission Control".
This will take you to the heart of Xcom's base. Partly an intelligence network, partly a personal debriefing room to you, here is the only place where you can actively "pass time", scanning the earth for extra-terrestial activity and waiting for building objects, research and engineering constructions to complete.
It's also a dillydally timer for you to use in order to get closer to having a "payday". At the end of every month, countries across the world whom you have established sattelites over along with a hidden and unnamned agency will give you money for your efforts.
Constructions in particular will notice you when they are finished.
In this case, the access lift to the second floor is done.
Following that, we further excavate the base to allow even more extensive building.
The research department will also need a constant management over current active projects and future ones. If you are uncertain of precise planning to your needs other than this guide, you may visit the game wiki in order to have the game "tech tree" on a chart.
For now, we are going to buy a handful of satellites all at once because they come in bulk and building one each time is very time burning as they take a whopping 20 days to complete.
If you made some sort of economical mistake or just need more dosh, simply visit the grey market to sell off any alien bodies, materials or other constructs you have gained through executing missions.
Eventually, however, when passing time, you will get missions assigned to you. Here we have a case of alien abductions taking place.
This is the point where I cannot perfectly guide you through the game anymore. MIssions assigned to you often have three variables to follow. Here we have a mission in Canada which has a 1/5 panic rating, an easy difficulty and a reward of 4 engineers.
While in Germany, we have 1/5 panic, Easy and a 200€ paycheck waiting us.
India also has a similar situation where the reward is instead 4 scientists.
To best serve our long-term interest in expanding the base best as humany possible, we're going to take Canada as a starting point for the extra engineers. That will unlock more buildings to be constructed which we have been aiming for through rapid excavation.