What will I built? Simple base building RTS

Something like simpler version of Rimworld/DF with Z levels and coop multiplayer support. Maybe just couple Z levels (and no world map).

As for background, I’ve professionally programmed for 10+ years and still do, so I’l work on this in the spare time. On work I don’t use c++, but I still consider quite comfortable working with it, especially after making helper functions to make life easier.

Foreseeable difficulties:
a) Automatic testing. Gauntlet seems not to be documented too well(especially if you don’t want to spare HDD space for Elemental demo) and it requires packaging.
So I’ll probably will end up using fake PlayerControllers, call inputs as if it were entered by players
b) models. So far the plan is to use simple geometrical shapes, like cones for bodies, ellipsoids for head/feet/hands
c) modding. Ideally there should be support for it. UE support User Generated Content, so at least there’s something.
d) non hotseat multiplayer: let’s say the cap is 100 units for players’ side + 100 for enemies + 200 animals. That can easily eat a lot of bandwidth if they all are moving.
e) fps death. Both RW and DF start lagging eventually, which seems no-no for multiplayer game, so game needs to be simplified and split to as many threads as possible.
f) lack of spare time. Coming from work at ~20:00 leaves me 4-6 hours of spare time per whole day before I need to go to the bed as pushing it further will cause sleep deprivation. And I also need to bathe, eat and watch funny cat videos.