ADOM was my first. It's not necessarily the easiest, but I found it fairly intuitive, and structure-wise it's more similar to most CRPGs than to real Roguelikes. The ASCII graphics are also some of the clearest and easiest to understand that I've seen.
This. The structure is really user friendly and, what is most important, you only need to learn a handful of keybindings to play it:
(o) Numpad keys for movement (includinng 5 for wait)
(o) < and > to ascend, descend stairs, or go into a wilderness square.
(o) l -> to 'l'ook at stuff, read up the monster description for clues.
(o) i -> to display inventory, equip stuff here.
(o) a -> to apply your skills (f.e. Detect Traps).
(o) t -> to use missle weapons, if you have them equipped.
(o) r -> to read magical scrolls and
(o) d -> to drink potions
(o) e -> to eat stuff (corpses are edible, but some may have bad effects)
(o) k - to kick stuff, kicking children may be fun, but it's main use is to kick down locked doors.
(o) Shift + T -> to change tactics - trade defensive ability for offensive, and vice versa - saves live in tough fights.
(o) Shift + Z -> select spell to cast (you may have to choose direction (including 5 - you ) afterwards) - to do it you must first read a spellbook a couple of times
(o) Shift + C -> to talk to stuff, useful for quests, sometimes enemies say something funny.
(o) ? -> for in-game manual, if you need to recall a more obscure keybinding.
Hints:
For starters, I recommend playing a Priest, detect item status is a p. cool skill for beginners, as you know what stuf you can safely equip. They also have healing, magic ability and are reasonably tough.
This class is best for experimenting, as you have access to most of the options.
For race, try dwarf (for toughness and detect traps), drakeling (for food preservation) or orc if you feel adventurous.
Visit the small village to stock on food
(you pickup things from the store, then 'p'ay the shopkeeper), then go south (not northeast) until you find a * which should read "strangely distorted cave entry", practice there until you feel comfortable. Don't try to go too deep, just switch levels until you're comfortable, they all should be randomized (it's a unique feature for this dungeon).
What else, door traps is one hated adom feature, if you see a locked door, be wary, as it may be trapped, and trap effect vary from 'mild stunning zap'' to 'burn all your fricken valuables fireball', that's why you may want to have Detect Traps skill, avoid the door if possible, and if all else fails,cautiously kick the door down from a diagonal position.
