After completing XCOM: EW on Classic with Ironman enabled, I thought doing a similar run in Sentinels.
Obviously there isn't such a mode in Sentinels, and the gameplay is different, thus I'll make a set of own rules and difficulty settings. These are the difficulty changes I'll make compared to my "Impossible run":
-Enemy AP: 160% -> 120%
-Enemy VP: 200% -> 160%
-Enemy level: +3 -> +2
-Enemy damage: 200% -> 140%
-Enemy hides: Always -> Never (And to compensate, I won't hide either. Apart from Scout class soldiers.
-Player damage: 50% -> 80%
-Weapon durability: 200% -> 200%
-Save possible: Real-time. -> Always *
-Healing: Based on skill. -> Based on skill.
-Hidden Random Encounters: Off -> On **
-Manual Casuality EVAC: On. -> On.
* I will manually save the game once every 5 turns, and immediately if a squad mate takes a hit / dies. If the main hero dies, I am allowed to reload the previous save (The main hero is 'immortal' - but can get wounded.) I am allowed to save while in base.
I am allowed to split two specific missions in half, and restart them from the mid-point (due to the arguable RNG-based events. And even XCOM: EW allowed restarts during base defense and Temple assault )
The missions: Peneemunde archieves (Finale room) and UN Bomb Squad (Finale room). I'm also allowed to restart the final mission (if I reach it).
** No level up / money grinding with random encounters. Although if I accidentally get into one, I am forced to clear the area / flee.
*** The shopkeeper can't be used to maintenance weaponry.
**** Bank robbery is a crime.
5* The Amber room belongs to the museum.
6* Save-scumming IS allowed when defusing mines set by own engineer.