One thing I will advise people to do if they want a more genuine classic X-COM experience is turn off the enemy health bars. It sounds like a small thing but it actually adds a whole lot of tension to the game in my view. When you see a Muton with its 12 red health pips you start treating each encounter like a math equation: "Okay my assualt rifle with knock of this many pips, dude with the laser rifle can get this many, then a grenade will do 3 more...etc". In classic X-COM part of what made encounters with the tougher aliens so terrifyingly intense was you never knew just how much pounding you had to do to kill it - you just moved your squad in firing range and hoped enough would hit with enough damage to put it out of action before it the aliens' turn.
After I figured out how to do it it made a HUGE difference in the battles, and they feel way closer to the classic X-COM fights.
“The greatness of a nation and its moral progress can be judged by the way its animals are treated.” - Mahatma Gandhi