Impossible difficulty (month by month guide)

Start game in Africa

-perfect mission-

1st base:
build order on first level:
training school - uplink - uplink - lift - workshop - power generator - power generator
excavate towards workshop by the lift
research: weapon fragments (scope)
for next mission allow panic to spike up in south america when choosing abduction locations, focus on doing missions outside south america and missions with engineers as a reward
-> mission control scanning (preferrably: ufo abduction mission)

-perfect ufo abduction mission-

2nd base
build workshop
research: alien materials (nano-fiber vest)
buy 3 sattelites (sell all sectoid corpses to do it)
await next mission to start the workshop if no cash, but pay attention to month timeline so the uplink can be completed before the end of the month
for next mission continue to avoid south america, pick the one in of of rpanicked countries regardless of the reward, that will minimize amount of panicked countries from 4 to 3 by the end of the month
-> mission control scanning (preferrably: coucil mission in one of panicked countries)

-perfect council mission-

3rd base
if workshop was not started due to lack of funds, start it now
-> mission control scanning (preferrably: ufo crash site mission)

-perfect ufo crash site mission-

4rd base
sell ufo flight computer and ufo power source for cash
buy satellite 4 and save cash for satellite uplink once workshop is completed
after satellite uplink is started, sell alien corpses to excavate towards power generator
research: meld recombination
for next mission continue to avoid south america, pick engineers or scientists as a reward
-> mission control scanning (preferrably: ufo abduction mission in one of panicked countries)

-perfect ufo abduction mission-

5th base
after satellite uplink is started, sell alien corpses to excavate towards power generator
-> mission control scanning (preferrably: remaining engineers to reach 20 or scientists, avoid requests with satellites)

-request completed-

6th base
research: beam weapons
build power generator (sell alien corpses in gray market for cash)
after completing power generator, build access lift (sell alien corpses in gray market for cash)
deploy the satellites in panicked countries before the council meeting


goals for next month:
- 3 more sattelites before the end of the month
- interceptor
- officer training school and cybernetics lab
- satellite uplink

1st base
after report buy 3 satellites and 1 interceptor, excavate towards power generator
-> mission control scanning
when lift is ready, excavate on both sides
for the next mission we pass up on north american countries, aim for missions with cash reward and try to pick either asian or european country, if both come up as an option - reroll until you have american, african and either asian or european
-> mission control scanning (preferrably: ufo abduction mission)

-perfect ufo abduction mission-

2nd base
build order on second level: alien containment - uplink - uplink - lift - cybernetics lab - power generator - power generator
for now build power generator and cybernetics lab, then excavate towards another power generator and another uplink, possibly up to alien containment
buy 1 medkit and 1 satellite
-> mission control scanning (preferrably: council mission, operation progeny: portent)

-perfect council mission-

3rd base
-> mission control scanning
when power generator is built, excavate towards the last one on second level and build another power generator and satellite uplink
at this point all second level should be in progress of either excavating or building
sell alien corpses to build the lift
-> mission control scanning
when cybernetics lab is built, sell some alien corpses to augument 3 soldiers
-> mission control scanning (preferrably: ufo crash site mission)

-perfect ufo crash site mission-

4th base
-> mission control scanning
after lift is completed, sell alien nav computer and ufo power source to build workshop by the lift on third level (for adjacency bonus)
next goal: await soldier augumentation to build first mechs
before scanning for the next mission save the game. you will need to rollfor abduction mission that will result in the least panicked countries across the continents AND provide you with engineers. Example: if you have already one panicked country in one continent and one about to be in the same continent, this one needs to be prioritized as you will not be able to deploy 5 satellites before the end of the month, it is better to spread the panic levels around now so you have more time to save all countries in the long run
if that strategy is not possible, mind that "all countries saved" run is no longer possible but you are not losing continent bonus if you don't deploy satellite in africa
-> mission control scanning (preferrably: ufo abduction mission)

-perfect ufo abduction mission-

5th base
-> mission control scanning (preferrably: council request)
at this point you should have 5 countries in panic, all north america and parts of africa, 1 satellite ready to launch and 4 more in production by the end of the month, so you should be set
However!
game should drop you a lifeline at this point in the form of council request mission to deploy satellite. Now you should save the game and continue as follows:
if you play impossible without ironman it is worth a risk to take that mission as this way you deploy the satellite as you would normally by the end of the month and on top of that you get cash
if you play ironman, I consider it a risk worth mentioning here, as by the end of the month country may go into panic again, undoing the "no countries lost" run
weighing pros and cons I suggest taking the satellite request as the cash reward is worth it and you end up with one less country in panic, other requests grant far less cash and no panic reduction
when it comes to choosing the preferred country, I take the north american over the african one because you can take the risk of dropping any of the african countries by the end of the month as you still keep the cobtinent bonus and do not endanger losing the game this way at this point
regardless of your choice, you should end up with one satellite deployed, one less country in panic, 200 in cash and 4 satellites in production by the end of the month
going forwards I will continue the guide as if that option was picked
for the acquired cash buy 1 satellite, 1 interceptor and build officer training school
-> mission control scanning (preferrably: council mission, operation slingshot: friends in low places)

-perfect council mission-

6th base
build order on third level: genetics lab - uplink - uplink - lift - workshop - foundry - power generator
build last power generator on second level and excavate two spaces on third level on both sides of the lift
-> mission control scanning
once soldiers are augumented, construct 3 mechs and assign abilities in barracks; you should now be able to start your first terror mission with two mechs
-> mission control scanning (preferrably: terror mission)

-perfect terror mission-

-> mission control scanning
research: experimental warfare (foundry, phoenix cannon)
sell alien corpses to build uplink on second level
deploy the satellites in panicked countries before the council meeting

1st base
build first uplink on level 3 and keep excavating on both sides of the lift
buy 4 laser rifles and 2 laser pistols
officer training school: squad size I and II upgrades, Iron Will
-> mission control scanning
research: xenobiology
sell alien corpses and build foundry
-> mission control scanning
once research completed, do all of the instant autopsies
research: arc thrower
for the next abduction mission pick cash reward and country on continent, which is least panicked; this month we allow panic to spread in more panicked continent
-> mission control scanning (preferrably: ufo abduction mission)

-perfect ufo abduction mission-

2nd base
!important!: it is possible for large ship to appear over one continent in the following days, to prepare for it scan few days to anticipate where will it appear, then reload the game to this point and move additional interceptor from any othe continent - it will take two interceptors and the following preparations to take it down:
buy x5 phoenix cannons and equip interceptors
-> mission control scanning
move one interceptor over the needed continent
after excavation, build power generator on level 3
instant research any alien corpses
buy 1 satellite, 1 defense matrix, 1 uplink targetting
-> mission control scanning (preferrably: ufo crash site mission - use 2 interceptors to take it down)

-perfect ufo crash site mission-

3rd base
buy 1 interceptor
-> mission control scanning
after power generator is built, build alien containment, if you need cash sell alien corpses - do not capture alive aliens until it is built!
-> mission control scanning (preferrably: council mission: bomb disposal, cash reward)

-perfect council mission-

4th base
excavate last slot in level 3 and build lift to level 4
-> mission control scanning
after researching arc thrower research: heavy laser
buy 1 arc thrower
-> mission control scanning (preferrably: council mission: confounding light)

-perfect council mission-

5th base
equip interceptor with phoenix cannon
buy 1 interceptor
buy Lead By Example upgrade from Officer Training School, sell some alien corpses if low on cash
-> mission control scanning
EXALT covert mission should now be available, send your operative
-> mission control scanning (preferrably: ufo crash site mission - 1 interceptor should be enough)

-perfect ufo crash site mission-

6th base
-> mission control scanning (preferrably: council mission: gangplank)

-perfect council mission-

7th base
instant cyberdisc autopsy
-> mission control scanning
build the last remaining satellite from cash from rebates; with one withdrawn countries you will need no more uplinks and satellites
-> mission control scanning (preferrably: covert ops EXALT)

-perfect covert ops EXALT mission-

8th base
build order on fourth level: - power generator
start to excavate fourth level towards power generator
-> mission control scanning (preferrably: ufo abduction mission, cash reward)

-perfect ufo abduction mission-

9th base
foundry: alien grenades, heavy weapons platform
buy Wet Work upgrade from Officer Training School
instant interrogate aliens and continue research heavy lasers
-> mission control scanning
deploy satellites and deploy interceptor to the last continen without it

1st base
excavate both sides of the lift
foundry: tactical rigging, ammo conservation
-> mission control scanning
research: outsider shard
buy x5 laser cannons and equip interceptors
buy x3 railguns and x3 heavy lasers and equip soldiers
scan for EXALT and send operative
buy x5 S.C.O.P.E.
-> mission control scanning (preferrably: ufo crash site mission)

-perfect ufo crash site mission-

2nd base
instant autopsies and interrogations
-> mission control scanning (preferrably: covert ops EXALT mission)

-perfect covert ops EXALT mission-

3rd base
build power generator
scan for EXALT and send operative
foundry: advanced servomotors, mec close combat
-> mission control scanning
research: ufo power source
buy 1 skeleton key
-> mission control scanning (preferrably: alien base assault)

-perfect alien base assault-

4th base
instant sectoid commander autopsy then research power source
-> mission control scanning
deploy the last satellite
-> mission control scanning
as soon as the power generator is completed build: laboratory, genetics lab, psionic lab, power generator
-> mission control scanning (preferrably: covert ops EXALT mission)

-perfect covert ops EXALT mission-

5th base
-> mission control scanning
after ufo power source resarch is completed, research: alien nav computer
you can now upgrade all mechs (depending on whether you want to upgrade mechs)
-> mission control scanning (preferrably: council mission: site recon)

-perfect council mission-

6th base
buy 1 S.H.I.V. to let it be destroyed in any mission and unlock the defender medal (optional)
-> mission control scanning
after alien nav computer resarch is completed, research: new fighter craft
-> mission control scanning (preferrably: terror mission)

-perfect terror mission-

7th base
sell some alien corpses and buy Rapid Recovery from Officer Training School
-> mission control scanning (preferrably: ufo crash site mission)

-perfect ufo crash site mission-

8th base
-> mission control scanning
sell alien corpses to excavate 4th level (optional)
-> mission control scanning (preferrably: base defense mission)

-base defense mission-

9th base
foundry: S.C.O.P.E. upgrade
-> mission control scanning
when Psionic Lab is built, assign 3 soldiers for psionics
excavate level 4 for cash from rebates if not done yet
-> mission control scanning

!important note to remember for the month!
at some point during this month, new alien craft may appear over one of the countries. I was unlucky to receive UFO contact over the continent I did not have firestorm coverage over and that UFO craft was not possible to take on with regular interceptor. If you happen to have this situtuation in your game, simply ignore contact and game on, another UFO is going to keep coming back to that specific country during the game. Simply transfer one of the firestorms and once its there, it will destroy the UFO once it comes back so panic won\t keep increasing
another thing: EXALT missions. Always keep your game saved before hitting mission scanning so you avoid EXALT surprises, even if you cannot scan for cash
yet another thing: I avoid navigating through the MELD spending or psi upgrades as I consider these optional as opposed to MECs, which are basically the only tanky soldiers at this point of the game, however I strongly advise to test as soon and as many soldiers possible and then to level them up in psi abilities each mission

1st base
finish excavating 4th level
scan for EXALT and send the operative
buy New Guy upgrade in Officer Training School
-> mission control scanning
after new fighter craft research is done, research: plasma rifle
buy x3 firestorms
-> mission control scanning (preferrably: ufo crash site mission)

-perfect ufo crash site mission-

2nd base

scan for EXALT cell (optional)
-> mission control scanning (preferrably: covert ops EXALT mission)

-perfect covert ops EXALT mission-

3rd base
foundry: shaped armor, stealth satellites
build laboratory
-> mission control scanning (preferrably: council mission: deluge)

-perfect council mission-

4th base
assign abilities to new recruit
scan for EXALT cell (optional)
-> mission control scanning
after plasma rifle research start research: heavy plasma
buy 4x plasma rifles
-> mission control scanning
after heavy plasma research start research: plasma cannon
deploy over continents 3 firestorm and build 2 more
-> mission control scanning
after plasma cannon research start research: plasma sniper
buy x5 plasma cannons and equip all interceptors
-> mission control scanning (preferrably: terror mission)

-perfect terror mission-

5th base
scan for EXALT cell (optional)
-> mission control scanning
after plasma sniper research start research: carapace armor
-> mission control scanning (preferrably: ufo crash site mission - yep, it's that UFO I mentioned at the beginning of this months description)

-perfect ufo crash site mission-

6th base
-> mission control scanning (preferrably: covert ops EXALT mission)

-perfect covert ops EXALT mission-

7th base
-> mission control scanning
after carapace armor research start research: elerium
-> mission control scanning

1st base
buy x3 particle cannon, x2 plasma sniper rifle, x1 heavy plasma and equip soldiers
-> mission control scanning
after elerium research start research: titan armor
foundry: improved arc thrower
-> mission control scanning
when firestorms are built arm them with plasma cannons and deploy over the continents
-> mission control scanning
after titan armor research start research: hyperwave communication
upgrade one mech (optional)
scan for EXALT cell
sell alien corpses to hire 3 soldiers for psi testing (optional)
-> mission control scanning (preferrably: council mission: furies)

-perfect council mission-

2nd base
assign abilities and add all 3 soldiers gained as a mission reward to psi labs testing
-> mission control scanning
after hyperwave communication research start research: fusion lance
it is possible to build hyperwave relay now, but in this guide I will postpone it due to lack of finances to buy armor to my soldiers and do some more missions to upgrade psi soldiers before taking on the Ethereal alien. It is however possible to sell alien corpses and start building the hyperwave relay at this point of the game
-> mission control scanning (preferrably: ufo crash site mission)

-perfect ufo crash site mission-

3rd base
if you had any new recruits, now is a good time to put them through psi testing if it's not done already (optional)
-> mission control scanning (preferrably: covert ops EXALT mission)

-perfect covert ops EXALT mission-

4th base
scan for EXALT cell (optional)
by now you should have only two countries left but for the sake of XP i propose to wait for one more covert op
-> mission control scanning
after fusion lance research start research: ghost armor
build hyperwave relay
sell some alien corpses to buy x5 fusion lance and equip firestorms
!note! at this point of the game the only essential research is alloy cannon, guided fusion launcher and plasma pistol and there is not any essential, for the purpose of this guide, foundry upgrade so I suggest selling some alien corpses and EXALT gear on grey market to buy fusion lance and equip the firestorms, which would end the subject of the upgrades for flight crafts for the rest of the game
!note! hyperwave relay should be done before the end of the month so at this stage of the game try to level up as much psi soldiers as you can as you will be able to do so safely with no sectopods around
-> mission control scanning
after ghost armor research start research: alloy cannon
scan for EXALT cell (optional) (optional)
-> mission control scanning
if you happen to have any council request for 600 cash or more, fulfill it with cash you get from selling alien corpses and after fulfilling it buy x3 ghost armor
-> mission control scanning (preferrably: terror mission)

-perfect terror mission-

5th base
you can upgrade second mech to level 3 with cash from grey market (optional)
-> mission control scanning
after alloy cannon research start research: plasma pistol
-> mission control scanning (preferrably: covert ops EXALT mission)

-perfect covert ops EXALT mission-

6th base
with cash on hand, additionally sell some alien corpses to buy 1 ghost armor
equip four of your soldiers fully with ghost armor and plasma weapons and try to complete every mission from now on with that squad plus two MECs - the endgame begins
-> mission control scanning (preferrably: ufo crash site mission)

-perfect ufo crash site mission-

7th base
-> mission control scanning
after plasma pistol research start research: guided fusion launcher
-> mission control scanning
after hyperwave relay is built it is possible to face off with the overseer ufo before the end of the month as it happened in my playthrough - a nice final touch before rounding up the monthly report
-> mission control scanning (preferrably: ufo crash site mission - an overseer ufo)

-perfect ufo crash site mission-

8th base
instant interrogations and autopsies
-> mission control scanning
after guided fusion launcher research start research: ethereal device
-> mission control scanning

1st base
-> mission control scanning
after ethereal device research start research: psi armor
build gollop chamber, if not enough power - remove laboratory, build power generator and gollop chamber
-> mission control scanning
after psi armor is researched, I consider this guide to be finished - at this point every key upgrade is made, gollop chamber is in the process of being built and after income influx there is enough money to buy alloy rifles, psi armors, plasma rocket launcher, mech upgrade and equipmnet like mind shield as to your liking. This is the point where I am leaving this game in your hands.

Good luck, commander!