There's also Brogue Speak, which is a customized version of Brogue with an audio interface. Dungeon Crawl Stone Soup is mostly accessible by default, and is an excellent roguelike with lots of classes to choose from.

More generally, any roguelike which runs in the text console is playable. If you have acces to a Linux system, either real or virtual, my favorite becomes available, Cataclysm: Dark Days Ahead.

There are some decent rogue-likes in both the glulx and Z-machine formats. For glulx, there is Kerkerkruip which is a very strategic exercise in choices. Victor Gijsbers uses philosophy to assist in his game design, so his games tend to be kind of interesting in the sense that they are designed around a certain design element. In this game, it's depth through choice of actions with different benefits and some risk management. Another one from the Z-machine is a game called A Little Like Rogue (Creative name, I know.) It's pretty could for a good run I suppose. Not as good as Kerkerkruip, though. The file on the interactive fiction archive is llr3.z8. It spawns a simple dungeon that you can walk around. Admittedly, the floors are either squares, or streight lines. Sometimes you might get half a square. We've also got Wumpus 2001. It's not that bad, either. I guess it falls a little away from the rogue-like thing, though. They adhere to the formula as well as Z-machine games can. Either way, Wumpus 2001 is definitely more exploration heavy than the others.
Anyways. Hope that helps.

Part of Entombed's design involves making the most of what you get rather  than choosing optimal conditions, this is why some race/job combos are intentionally harder to work with and you need to give right secondary jobs to compensate.

The goblin king however is not that tough, so something suggests to me that your doing something fundamentally wrong in how your playing the game.

Possible newbie mistakes include 1: not comparing equipment you find to end up with better (all items are unique therefore two good bronze short swords are not equal).

2: trying to combine magic and technique based jobs. Since magic jobs increase mental stats per level and technique jobs increase physical ones, this is just a combo that will not work, since a fighter mage ends up being half as powerful as either a fighter assassin or a mage necro.

3: Not distributing skill points correctly. Since you have no choice about who is attacked when, putting points into armour types is a waste of time, it's better to concentrate on attack skills. Also, don't put points into a weapon skill unless you can be sure of having a good version of that weapon (short swords is good).

Also, distribute the points around.

4: Forget to use targeting especially with magic. ice blast to the head can make the game almost a one attack slug fest, particularly since magic never misses even if you aim for difficult head shots (yes, this is a huuuuge! imbalance and does make magic jobs better than technique ones).

5: Forget to rest. There is literally no reason not to rest after each fight as there are no penalties for resting, save healing potions for battles.

6:Target the same enemy. If an enemy is up and fighting they are damaging you. Focus  on one enemy at a time with all your party. The one exception to this is if you have a spell like sleep or a knockdown attack that  decrease another enemy's effectiveness, also remember any defensive techniques such as sneak attack that put your characters out of the line of fire are going to be useful.

7: Remember cooldown timers. Flurry sneak attack looks like an awesome combo, however it's going to put your fighter out of action for a while. Usually I only do this if I can be sure of killing an enemy or if I want some payback.

if all else fails, try an elf necro healer, or if you've unlocked it necro druid. Ice blast to the head plus a skeletal companion equals an easy trip through the dungeon.

if you get a fighter, make them  an assassin or thief (assassin  critical hits and sneak attack makes a good combo with any physical job), and if they're a race not suited to be physical fighters like Halfling or they can't be assassins try bard, indeed Bard is  a pretty overpowered job generally whether as primary or secondary.

if they are a magic job, make them a necro or druid.

Remember that though half orc and ogre are nominally easier options, the dungeon races generally have a harder game since your more likely to rescue something useless like a goblin or Kobold or ogre mage.
Hmmm, writing this makes me want to go back to my entombed handbook project.

hth.