Realtime needs player AI, your soldiers need to do more then just execute the last command. This means they should be able to engage the enemy on their own, take cover if under fire, switch equipment as needed, switch targets as needed etc etc. Without this it can become even more a case of micro management then the turnbased game.
Apocalypse did it nearly all right. A soldier on their own would attack any enemy, switch to the most dangerous one, take cover behind anything close if needed. This made for some of the most intresting battles I ever seen in a computer game.
So what is needed to make a true semi-realtime UFO/X-Com sequel.
You are the commander, selected from thousands of other ordinary human beings by the X-com project (the original games were just a training program) you have been chosen to be the tactical brain behind a program setup to deal with the increasing numbers of alien sightings.
The first part of the game functions as the tutorial and sees you being asked to deal with several early missions involving events that may be related to the increased number of sightings, including investigating several human organisations.
The X-com organisation has you making the tactical decisions with overall strategic orders coming from the various real world organisations, your task is to keep your real agenda (keeping the world out of alien control) with appeasing those who fund your program. Not all of them share the same goal, or even your goal.
Early on their is also demand that you keep your actions as secretive as possible for risk of finding to many opposed to you.
In the beginning you find yourselve equipped with real world weapons for your combat missions. Resources are limited but realistic, you are outfitted as a small special forces team could be expected to be. You got high quality equipment, basics in ready supply (No special forces unit in the real world needs to hustle for bullets) but limited in scope. Your currency for improving this is NOT just money but also goodwill with various real world organisations, if the US likes you, expect a carrier force to be assigned to your unit, if the USSR likes you, you may get advanced air transport capabilities, the Israeli's like you, you get advanced intelligence, the arabs supply more money then you could hope to spend, etc etc.
Offcourse their are counters to this as well, not everyone will like you to be friendly with their enemy, especially if they perceive your actions to harm them.
Before a mission becomes available your job is to insruct your scientists to research what tech you find most desirable, instruct engineers to use this research to augment your gear and to train your soldiers in prepration for the next mission.
Your soldiers are an entire segment of management on their own, soldiers who are injured need to heal BUT can also spend time studying during that (slows the healing somewhat but wastes less time) Soldiers on intensive training are not available for combat until finished while on-site study might see them ready in a couple of hours. Ready teams can be instantly deployed, but the constant pressure wears them out.
Then there is the question of deployment, your main base has the best facilities but makes it hard to respond quickly to events in remote corners of the world.
When an mission occurs your first decision will be to decide to respond or not. Make an attack to stop an alien take over of the vatican and you might just give youreselve a load of bad press, while a similar assault on the pentagon (if the US is friendly to you) might be far more acceptable. (Hush it up as a terrorist strike)
Then comes the question of what units will respond and how long you will wait before the attack will commence. Do you take the small elite team and drop them by parachute, use local agents, take the time to get a proper force ready. An option is also to attack with the first squad to arrive, then as combat takes place reinforcements could arrive.
Further tactical decisions are what back up forces to deploy, Evac choppers, gun-ships, civilian rescue teams.
The combat area itself is fairly large to accomadate real world tactics and the use of light support vehicles, they should also be random like the original X-com games. Combat starts with you having to insert your forces, this changes by the mode of transportation. Parachute drop, helicopter insertion or just driving in from a corner of the map.
The insertion is for the first time a real part of the battle, as the parachute drop will see your forces scattered over the map and a helicopter drop gives you the firepower of the chopper to clear the landing area.
Once your troops are on the ground they form themselves into small squads as dictated by their role, machine gunner team, mortar team, sniper duo etc etc.
Typically a mission will see you first move your combat units (not individual soldiers) to secure the drop zone, then proceed with the mission objective. Units are given directions of were to go, and how to get there, typically you want to move as fast as possible until combat starts. The units however will use their OWN AI to execute their orders and change them as needed. A soldier being told to run down a corridor will STOP and open fire if an enemy appears. Soldiers receiving fire will not slowly walk to their destination, they will either speed up returning fire on the move if possible, or crouch down and return fire or try to get to their destination under cover.
Not all units are combat units and for larger missions you mind find medical forces and other support units who need to be escorted and protected.