What's the key to failure in roguelikes?
I've tried a fair amount of roguelikes. Nethack, ADoM, ToME, Crawl and more. However, I can only very rarely got into midgame. My records, for example, are reaching the beginning of the Quest in Nethack (exactly once) or reaching Snake:4 at xl15 in Crawl.
What is the key to failure in roguelikes -- the basic, conceptual strategic mistakes that I and others do when approaching this kind of games?
Solution 1:
Obviously, there are game-specific gotchas, but here are a few common themes that come back to bite me over and over.
Moving on to a dungeon level which is too hard. Pretty simple, but gets me all the time: deeper dungeons have harder monsters. It's easy to get excited and move on to a deeper level of Nethack prematurely. If you're out of your depth, it suddenly becomes much more likely that a situation will arise that you can't deal with. For example, a common one is being surrounded by monsters which you could just about handle individually. En masse, it's all over.
Inadequate escape mechanisms. If you don't have a reasonable way to escape from a sticky situation, then it's only a matter of time before one catches up with you. In ToME, for example, Phase Door (scrolls or spell) is an essential tool. A variation on this is not having enough escape methods. For example, if you only have one Phase Door scroll, then it could easily be destroyed by fire, leaving you without an exit strategy if it gets nasty.
Missing key immunities. You can only make it so far in most Rogue-likes before a serious effect or damage type will take you out. For example, without resistance to blindness, confusion or paralyzation, later levels of Nethack are effectively impossible. Tol Falas in ToME is extremely difficult to finish without an effective way to manage high level magic-wielding monsters.
Single strategy combat. Most characters specialise in one form of combat. This works really well... until the moment it doesn't. More ToME examples: Your Super-Duper Ice Attack works great until you meet an Ice Drake. Your close combat berserking is perfectly adequate until you hit an Elder Vampire with a Phantasmal Shield. It's a really good idea to invest in several alternative methods for dealing with enemies, using ranged weapons, spells, magic items, dungeon traps, etc.
A false sense of security. When you've survived for a while, it's incredibly easy to drop your guard and get sloppy. It's easy to forget you are usually only a couple of (unfortunate) steps away from death. The classic one in Nethack is having your gloves burnt away while holding a petrifying corpse, or flying over a sink or something else equally stupid. In ToME, it's really easy to kill yourself by holding down a direction key on a long corridor, and failing to notice the Skeleton Mage at the other end blasting you with consecutive Manathrusts.
Solution 2:
This may sound cowardly, but I've found it to be good advice: Don't be afraid to run!
With many modern RPGs that I've played there is a general organization to the game that usually doesn't present you with anything too difficult for you to handle given your current level in the game, unless of course you're stupid enough to wander into places you clearly shouldn't be.
Conversely, some older roguelikes (like Nethack) can often randomly present you with creatures that are vastly beyond your current level or abilities. After playing many modern "balanced" games, you may think that anything you come across can be defeated with a little strategy, but this is probably not the right attitude to have for some of the games you listed. You have to keep in mind that at any given moment there is a non-zero chance that you could run into a very tough enemy. And flight is your friend in such a case.