Well, this is what I've currently hacked together for my Beyond the Wall game using a 5e chassis. Important point here is that I'm using variant healing rules, with a 6hr short rest and a 72 hr long rest.
1) Three classes, Warrior, Rogue, Mage. Only the Mage can cast.
2) No cantrips. However, the class does get invocations, some of which mimic non-damaging cantrips or groups of cantrips.
3) Standard 5e full-caster progression of spell slots, recovered on long rest.
4) Arcane Recovery once per short rest, recovering a number of slots equal to your level. (At level 5, can recover a 3 and a 2, or 5 1s, or anything in between).
5) No spell list. Mages can only cast spells they've acquired during their adventures.