The eternal tutorial. This mostly applies to Nintendo games, of whom the company seems to be fine with treating everyone as if they were three.

On the other end of the stick, games that don't allow you to make a simple mistake, as if you move one of your pawns even slightly wrong, your entire army is smashed apart. This is why I don't like TBS games.

The pointless quest: I'd prefer if like in Avernum, doing a quest is specifically to help someone, and not just a bizarre favor or fetch quest. If you have no need for the Amulet of Yendor, don't make me grab one for you.

This one mostly applies to Book of Eschalon. I don't like walking in real time. I get that my wizard may not be nimble, but surely he can manage something a bit swifter than a slow plod.

This is a common one, but for me, encumbrance is a pointless thing. Sure, I get that most people aren't actually pack mules in disguise, but just handwave it, please.

In FF5, you actually *can* create a black mage who can hit hard; just give your black mage an ability that provides Strength. This includes Barehanded (from Monk), Two-Handed (from Knight, though not particularly useful on a Black Mage), or most of the Equip weapon abilities. Similarly, if you give magic to a class like Knight, the magic command will provide some Magic Power (and MP, which is derived from Magic Power (not counting equipment) and Level).

Unfortunately, there's no ability that gives the character Stamina and HP. There is for Agility; Equip Bow and Harp both provide some if you don't want to master Thief yet.

There are lots of interesting builds in FF5 that aren't exactly obvious. Another one I found that I like is, late in the second world (after getting the Morning Star in the forest), give Two-Handed to a White or Time Mage. This gives you a character who can cast the nice spells you just bought (Curaga and Hastega are both really good) and who can use the Morning Star 2-handed with enough Strength to sometimes even outdamage fighter-types at that point in the game.

The ability to skip important items. Much as I love La-Mulana, many Let's Players didn't solve the puzzle for the Holy Grail. Aside from being a key McGuffin, it allowed the player to warp throughout the ruins. To say the least, anyone who skipped the Grail had a lot of walking to do.

Not just a lot of walking, but you're going to have to walk all the way back from the end of the game if you seriously forget to grab it.

But it's extra weird, seeing as one of the first video walkthoughs available shows the player (DeceasedCrab) getting both.

Walking is one thing, that important item flaw has been known to flat out kill games.

Didn't get the gizmo? Sorry, gotta start all over. Too bad you have 20 hours already invested. Better luck next time.

I have one game where it actually creates a bug in the game. If you don't get, or don't hold onto certain items, eventually all drops cease.

How about Quest for Glory 4's approach (which was a clear attempt to prevent this issue)? In QfG4, at least if you are playing a thief, if you enter the final area without the grapnel, the game gives it to you; it magically appears in your inventory. Might be immersion breaking, but much better than being unable to complete the game because you forgot something.

The skipping of key items brings to mind another issue: Optional content that expires if the player progresses the main plot. Worse, this content has no apparent signal for its availability, and often appears in a spot of the city that you have already explored. This pops up quite often in JRPGs, much to my disappointment.

Some go the extra mile and make the optional content have additional scenes that are spread throughout the world...without mentioning which location is next on the itinerary, nor being set on the next obvious step of the journey. These additional segments are also tied to a limited window of accessibility.

Great fun, backtracking everywhere for the Nth time and possibly getting nothing for it. :P

No way to remap keys, fixed volume music / background sounds, stingy on the save slots or worse save on exit.

Not being able to scroll with the mouse wheel through menus, especially on RPGs where you might have to do that a lot.

I understand why older games won't have that feature, but there's no excuse for newer titles.

Along the same vein; volume maxed on first start, and being unable to adjust options before X point, so if it started in the wrong resolution, sucks to be you.

Badly done ports. If you're porting from a console to the PC, please put in more than the token effort.

Taking forward the point about mousewheels in RPGs, You know what PCs have? Mice! I don't want to have to arrow-key through my entire inventory, or action menu or whatever. I have a mouse, and I want to use it! And yes, please have keys remappable, but aside from that, why not try streamlining your keys (or again, make greater use of the mouse!). I don't need the key to cycle backwards through my inventory screen to be different from the key to cycle backwards through my map waypoints, or reduce the volume in my sound menu, all of which are on separate screens.

Also echoing what was said about skippable, pausable cutscenes, savegames and QTEs.
And invisible walls! If your game is not an open-world, go-where-you-want RPG thing, maybe design your levels well to reflect that? All the "hacks" designers use just seem to be stopgaps for their badly designed levels: invisible walls, unsurmountable mountains, knee-high walls, "YOU ARE LEAVING THE MISSION AREA" messages, etc. If you designed it well in the first place, you wouldn't have this issue!

And a bit of a personal one, but if your game has (what is essentially a) "Don't play this game if you don't have a gamepad" at the start, then get lost. If I wanted to play games with the gamepad experience, I'd be playing console games. Platformers, fighting games, even damned flight-sims existed before there were gamepads for the PC (well, maybe not flight-sims without joysticks, but then that level of flight-sim isn't a "game"), and I played them great. A gamepad is not one of the standard devices that come with the usual PC setup. I prefaced this point with "personal", because I suppose it is less of an issue because many people have gamepads as a default part of their gaming PC setup, but I say it really shouldn't be. I mean, imagine if it became the norm for a game to be designed for "Don't play this game if you don't have a graphics tablet" or "Don't play this game if you don't have an eye-tracker".

I also hate when games force or even just encourage you to use gamepads. I don't have a gamepad, mostly because I expect a game built for a system that has a keyboard and mouse as its default control device to fully support a keyboard and mouse.

I am not sure if it is a matter of game design, but I (and everyone else, probably) agree that bad PC ports (which sometimes promote the above problem) should not be an issue when they are creating a product they expect to receive money for, and when there are already many other ports that are very well executed.

Not sure if most would call this a cardinal sin, but objects you can interact with or pick up NOT being highlighted in any way, especially if the environments are poorly lit, or objects don't tend to stand out much.

Also, the instances when your progress is hindered by something your character could logically overcome in seconds with their powers, tools or common sense. An example that bothers me, especially considering how great everything else was, is why, in Deus Ex, a door, identical to many other WOODEN doors like it, has infinite strength and is impossible to lockpick, when you might as well have used explosives or lockpicks on many other doors, some even more durable than it. (It was in that underground metro area).

Heh, a certain site has long lists of these, but you might lose a week or two if you decide to visit it.

Yep. But to me, that is a platformer means when it tells me "up is this key, jump is that other key".

I dont really find the "up is this key, jump is that other key", problem very annoying, though I often scratch my head and question the rationale behind that particular design choice. (I assume you must be referring to the side-scrolling kind).

Yes. No problem with that when up is "ahead" instead of "upwards".