Missions with pre-placed evac are like a quarter of them at most. I don't like it for not making sense, at least on the small scale of the maps in XCOM, but in terms of gameplay I think it'z a nice way to mix things up. One of the biggest problems with enemy unknown/ within was that missions got very samey very fast. This game does a good job of addressing that by having a decent handful of parameters including two ways to enter the engagement (stealthed or not) three to leave (kill all aliens, dynamic evac, or pre-placed evac) and can be timed or not. On top of that we've got dynamic reinforcements which not only contribute to this but tie the tactical level to the strategic level, and now we've got the monarchs, who tie one battle to the next in a fun and engaging way while doing even more to shake up the flow of the missions. Some of the details are slightly rough if you look too close, but overall it's a very polished game and a well designed system. Sometimes being kind of fucked if you can't pull off a miracle is a great improvement over the monotony of Enemy Unknown, and all Within did was add a bribe for not playing too cautiously, but didn't really add variety. I'd go so far as to say that the problem it was addressing was misdiagnosed, and XCOM2 does what shoulf have been done to start with.