First, some definitions:

A "seed" is the value used to seed the game's random number generator. In this context, "seed" can also be used to refer to the seed used to generate the dungeon. (In particular, if you play the same seed twice, the dungeon will be the same.) Some games allow you to specify a specific seed when starting a new game.

A seed is "solvable" if there is a sequence of moves that will result in the game being completed. (For example, in Rogue, such a sequence of moves would result in the player getting the Amulet of Yendor and successfully escaping the dungeon.) The sequence of moves can be called the "solution".

My question: Is it important that every seed be solvable, or is it OK if some seeds are not solvable? In other words, is it OK if, on any given playthrough, victory is not possible?

(Incidentally, Nethack has at least one unsolvable seed; it starts the player on a cross-aligned artifact that, with auto-pickup, is immediately picked up, and the damage from picking up the artifact kills the player before they get to make even a single move.)

So, your thoughts?

I don't think this can apply to today's roguelikes.

Majority of them should be winnable.
Otherwise, you're not making a hard game. You're making RNG-fuck-you-go-grind game; I'm looking at you, most retarded "roguelike" of recent years, Darkest Dungeon.

All seeds should be solvable.
If a seed make victory impossible, the programmer is not capable to write the game engine.
It is a bug and should be fixed.

Not all Minesweeper levels are solvable by logic, but all of them are solvable by luck.

I beleive All seeds lead to a solution in the algorithm, this is the rule of thumb this explained well in some platformes like . However if any issues rises that's would be
a bug , that should be fixed.

What are you talking about? Darkest Dungeon is great.

The fact that its turn based means you have the time to examine the choices and the stats and percentages and then you take your calculated chances.

As for grinding - the system might not be to your taste, but the whole challenge of the game is to get a roster of adventurers leveled up and geared up high enough to take on the Darkest Dungeon.

I think it's fun and challenging and not grindy at all. Unlike, say true Roguelikes, like Nethack, in which there is a ton of trial and error. By which I mean, you make guesses and you die as a result. Then you make a little mark in your notebook and start over. The only alternative to slowly and painstakingly creating your own notebook database is to use online guides. The game itself doesn't supply you with the info you need, except through trial and error.

In contrast, Darkest Dungeon displays enemies' health points, resistances, special attacks, etc. The map shows you how many rooms and in what arraangement. The only blind spots are the curios - its a guessing game as to what item might help you with each curio. But even then, the game remembers your previous choice and reminds you. And, the curios are consistent throughout the game, so once you know, you know.

When I first tried roguelikes* I was put off very quickly by my starting floor not having any way to proceed. I think that soured randomly generated content for me substantially. As such, I'd say yes, they should all be solvable.

(* Actually, I lie, it was the second time. I'd beaten part one of Castle of the Winds before that. I don't think I'd have recognised it as a roguelike rather than an RPG though.)

There are a couple games that, while not actually roguelikes, led me to make this topic. (They do share the idea of randomly generated levels, however.)

Syoban Action: There is a special mode, described as "Mystery Dungeon Mode" in the Japanese readme, that gives you random levels. Of note is that the level is re-generated if you die. Also of note is that the levels are frequently not solvable; even if you are able to reach the flagpole at the end of the level, there might not be enough ground for you to survive the end-of-level cutscene. In any case, beating this often requires a lot of patience until you get lucky with a solvable level. One thing of note is that this is not the main gameplay mode and is somewhat hidden (press the numeral '0' on the title screen to access this mode), and therefore the developers didn't put much effort into ensuring solvability (they at least guarantee a platform beneath the starting position, but sometimes even that's not enough to make the start safe).

Zelda: A Link to the Past Randomizer: This is a program that generates a romhack in which items have been shuffled around. One thing is that the randomizer uses what it calls "logic" in order to ensure that every seed is solvable (assuming you don't set the logic to "none", which is an option). Different logic settings make different assumptions about what glitches (if any) are to be used, as well as things like whether the player is required to go through dark rooms without a light source. While every seed (assuming logic != "none") is supposed to be solvable, there have been times when that's not been the case, or when using keys in a certain way could softlock you; I believe the developers of the randomizer have considered such cases to be bugs.

Solvable?
I don't think Dwarf Fortress is solvable.

Being not "solvable" would be realistic. Plain old Klondike solitaire is a perfect example. It is random and different with each deal. But, according to the Wikipedia page:

For a standard game of Klondike, drawing three cards at a time and placing no limit on the number of re-deals, the number of possible hands is more than 8 times 10 to the 67th power or an 8 followed by 67 zeros. About 79% of the games are theoretically winnable, but in practice, human players do not win 79% of games played, due to wrong moves that cause the game to become unwinnable.

As a lot of others already said, for me too, they should be always solvable.
I don't see the point in playing a game which should have a end, but that you can't reach because for this run, there isn't a "solution". I see this as an error of conception of the game.

Personally, I believe that every seed/session should be solvable but I am also aware that various obstacles (ie the game's monsters, traps and other 'puzzles') will make that victory difficult to achieve. The challenge of each randomly/procedurally generated world/universe is part-and-parcel for the genre (and, in some ways, part of the fun).

Being able to freely save and restore one's sessions can improve a player's chances of completing the game's (main) quest(s) and keep the experience enjoyable, overall, but keeping unfair obstacles/game mechanics to a minimum, if not optional, can help even further. ^_^

The last thing I'd want to do is spend 10,000+ hours exploring the world and beefing up my character/party only to be crushed/obliterated by an (invincible) winged karma creeper just after I'd found/picked up the McGuffin of Infinite Whatever. it's time that could have been spent rewarding myself in other (far more satisfying) ways.

(Believe me, the 'horror stories' I could tell about Minecraft's buggy [Survival] mode could go for pages) -_-

Question, when was the last time you played this? Or have you at all? Because a major update did just come out.

Oddly enough, I tried playing the newer version (1.13) yesterday and I can't say that I'm too impressed with the new [Buffet] method of world generation. e_o

While I'm sure the option to select a (starting?) biome and 'structure' (players can start in underground cave worlds or on floating islands, not just 'Surface' maps) is welcome, there doesn't appear to be any way to determine the size of the world or whether biomes are still mixed throughout the map(s).

Any seeds that I recorded (that didn't generate 'water worlds') no longer work so I'm going to wait a little while before attempting a future playthrough. ^_^U

If Mojang/Microsoft is testing new features for the game, it is my hope that they will re-add the [Custom] setting to the world generator and, possibly add an [Adventure] setting (preferably with peaceful Creepers) to the list of [Game Mode]s.

I like the idea of a large world/universe with many different places to explore and interact with, if not build upon.

However, I don't like investing hours of my time building a large self-sustaining underground fortress with rooftop farms and supplies to last for days or months (if not centuries) only to have it destroyed (and/or my character killed) by a lime-green louse. >_<

I play games to have fun...to reward myself for tolerating Life's tribulations not to seeth with rage at a game's flaws.

Until further improvements are made, I will likely give some other electronic distractions a try.

Perhaps a certain Glorkian Warrior or Outlander require my assistance?
Perhaps another trip through Limbo will do me some good?
Perhaps I should revisit some old 'haunts' in Terrortown?

Hmmm... ^_^

Isn't that just Survival on Peaceful difficulty?
The concept of playing something "wrong" under a blind setup is kind of stupid.