the images show region and country boxes
if a action happens over region/country it adds to xcom/ufo points
cities are assigned to regions so i assume a terrorattack count toward the assigned region not the region below (the cities jakart,ankara,teheran, caracas are technical on a region block that do not correspond with the assigned region for the city)
region/countries have an order
if a ufo flies over northamerica it checks its ground and goes through the country list and stops at the first hit to assign points
if canada would be first in the list half of the yellow-usa blocks would be under the big canada block
luckily usa is first in the list
region/counry have no direct influence over missionzones
of course they are placed so a flightpattern crosses over the relevant region often to make a lot of points for the alien
the missionzones also controls how often you can attack landed ufos in mountain terrain (not very often = unlikely odds)
how the engine works to my understanding:
- choose a region (if mission available)
- choose a mission from the region
- choose a race for the mission
- start the first ufo from the wave in alienMissions->waves
- each region has different zone declaration so an ufo with goal australia can appear first in europe but an ufo with goal europe has to appear somehwere else first
here is what the missionzones for a region look like
https://openxcom.org/forum/index.php?topic=2697.msg32032#msg32032- the ufo flies from waypoint to waypoint defined in trajectories each waypoint is randomly selected there a a bunch of possible boxes for each region-zone-entry and within the box there is a random selector for the exact waypoint
my guess is that in the pic of OP the ufo uses some trajectory with zone 5 for landing only there are multiple zone5 entries that do not have any land under it so if you define a mission in europe that lands in zone5 it can appear as a "water ufo" in the pacific
all other zones have at least some land coverage
with the exception of one zone0 entry in STR_PACIFIC so a modder should avoid allowing missions in region pacific with a trajectory that lands in zone0
