How is mission difficulty determined?

[Jon.Topps]

I'm just wondering, how is the difficulty determined? (i.e. how many enemies and what types they are).

I can think of a few ways, but I'd like to know for sure, to know what strategy I should take.
1. By the date (how many in-game days have passed).
2. By your progression through the game (whether you've downed a UFO, captured a living alien, attacked the alien base, etc.).
3. Level of squad (what rank your people are at).

I've read other people speculating on this, but nothing concrete (that I've found).
Some say it's how much in-game time has passed. So this means I could still have to interrogate a living alien as my mission, and I could be getting sectopod things everywhere?
Can anyone confirm how the mission difficulty and mobs are dictated?
Thanks for the help!

[red255]

mobs show up depending on the month and whether or not you are doing marathon mode.

the 'difficulty' rating purely refers to the amount of aliens on the map, 12 sectoids would be the same difficulty as 12 heavy floaters.

progression thru the main story only influences the captain pod of a UFO.

[Sacrilige!]

depending on the difficulty you play on stronger aliens will show up sooner like mutons in the third month or so when they usually come later.

The biggest factor is based on how many days have passed, the game expects you have have made new weapons, amour, etc by a certain amount of time and will not hold back if the player has neglected to reserach or make them.

Story mission make late game aliens more common such as the sectoid commander but they becoem more common regardless if enough time has passed.

as for difficulty, it random for the most part (the exception of terror mission which are always swarming) but they are also time related and 'swareming' mission will also become more common as more time passes.

So in short time is the biggest factor when what alien shows up and how many will be there

[red255]

month is the only factor. it is not the biggest factor. it is the only factor.

[Mutant Overlord]

cough Google exist cough
http://xcom.wikia.com/wiki/Game_difficulty_(XCOM:_Enemy_Unknown)

[Jon.Topps]

Originally posted by 暗黒卿 MUTANT OVERLORD:

cough Google exist cough
http://xcom.wikia.com/wiki/Game_difficulty_(XCOM:_Enemy_Unknown)

*cough* I was actually asking a different question, and that site doesn't help at all, and not only did I google my question, but I read a few forum posts about it, and even mentioned what others thought in my OP *cough*

[SamBC]

Mostly it's on month.

A couple of things are gated on game progression - the replacing of one enemy type with another happens twice based on that.