I really miss defense part of old xcom - in PP you can completely neglect it. Here’s how I would improve it while keeping it in line with PP mechanics and without xcom tedium.
- Base attacks come with no warning, as it should be - resources spent on defense will improve the outcome
- In order to avoid unit transport which is a pain, you can buy up to x defenders from single living quarters and they cost food to maintain. These guys are cannon fodder, I don’t want to equip them or deal with them - give them rookie class/basic equipment or similar
- Introduce Armory facility so I can buy/control what equipment they get and what level they will be (idea is easy resource management on base level) - better Armory better equipment & level
- Introduce facility blast door (explained below)
Enemy units spawn in both access lift and hangar with strong preference for one. Your defenders spawn around base with slight preference to ie living quarters. If you have your proper forces stationed, they spawn too. The objective of the mission is to separate your forces from the enemies by closing the blast doors or kill all enemies (easy at beginning, hard later). Mission is finished when all your soldiers are in a separate base “graph” with no living enemies there. If you fail, base is lost (generates a difficult “reclaim base” mission). If you succeed, you have set time to get your proper forces there and clean up the base of enemies. While timer is running, enemies are slowly destroying parts of the base they have access to.
Additional mechanics:
- As PP bases are randomly generated, some rooms need to be “exchangeable” - so ability to swap 2 rooms for small cost
- Having stronger preference for one point of entry gives player more choice in where to put blast doors as Hangars would hardly be swappable (especially early in the game when building/demolishing costs are too much). So if you can isolate both - great. Else isolate main point of entry if you’re on a budget.
- I suppose energy generators would be critical to protect as without them there is no power for the blast doors
- Perhaps the introduction of Corridor facility would not be bad to make defensive planning more interesting. Cheap to build but expensive to remove (what has been dug stays dug). Also would make room transfer cheaper/faster (dig a corridor, move lab there, the room lab was in becomes corridor)
).
Doing research on how it would affect fun factor, balance (
), cost (
), how many work-hours for devs and QA, is it safe in current architecture, risk & reward, sales and shitload of other things not related to coding is a challenge a company most likely will never release as an “improvement”. You are talking about base management refactor - we had to wait few months just to get PP bases in non-totally-random locations. 
