Yeah, apologies if it came off too harsh, but I generally subscribe to the school of thought that says you learn more from honest criticism than from softballing. If I thought that you were useless and would never make a good game, I wouldn't bother responding.
Okay. Hm. I'll try to break it down a bit more. Keep in mind that I've got closer ties to the /tg/ and Spacebattles style of forum game, which
is (to be fair) generally more narrative-oriented than a lot of what you find here, which tends to be a pretty sharp split between games with a lot of rollplaying and lulz, and "games" which are pretty much just an excuse for roleplaying, with relatively few "quest" style games. It also matters whether you're wanting to do a general forum game or an RTD, since RTDs by their nature are usually pretty simple mechanically, meaning that the popular ones tend to break down into minimalistic ones and really narrative-heavy ones.
But, ah, here we go:
1. The HookThis is your one shot at getting people interested in your game. Your first post should be straightforward, be easy to parse, and effectively convey what your premise is. Don't bog it down with paragraphs of information that people won't care about until they're invested in the game. This is one place where there's a lot to be said for the Quest model: generally players are presented with a fairly simple hook, usually consisting of the setting (this is why established settings are good: people are familiar with them without needing pages of description, and people who like the work the setting is from are more likely to stick around) and a set of choices to establish who the character is and what their basic traits are. You can tack on additional information after you've got people invested enough to care, typically because they've already helped decide on a character and been fed the first choices in the plot.
2. The SettingAs I've said repeatedly, established settings are good, both for the reasons above, and because they drastically decrease the workload on you. An established setting already has a world full of places and people, as well as an audience that cares about it. All you need to do is examine it to determine where and when your players might like to start their story, then present a selection of a few of those. As you progress, all you need to do is factcheck rather than establish every detail yourself. This saves time and helps restrain player griping, as the blame for stupid things in the setting isn't on your head (and you can, of course, trim that sort of fat from it if you wish).
Original settings are tricky. Not just because of how much work they take to do right and because nobody initially cares about them, but because the vast majority of such premises have already been done to death. If you've seen something like it on a forum games board in the past two months, it's probably not going to catch a lot of attention. If it's an extremely generic setting with nothing to catch player interest (as before, Zombie Apocalypse and Amnesiac are very, very common), it'll die from inactivity. The trick isn't necessarily to come up with something wholly original, but to at least put enough of an original spin on something that isn't
too overplayed that people will get interested long enough for you to secure their attention with good writing and an interesting plot.
3. The PlotYes, you need one. Or rather, you need events which occur independently of player action. There's a reason that the concept of a dungeon consisting solely of a string of unrelated rooms with irrational populations of monsters and treasure is so maligned: it's boring, generic, and doesn't make sense. Just about the only exception is when you're running a base-building style of game where you manage a community or installation of some sort in RTS style, and even there you need to have things happen without player prompting. Giving people a series of places to visit and events to trigger when they arrive at them isn't enough. Even if you don't go full-on storycrafting mode with your players (hopefully because they don't really want that), don't just line up a series of loot/exp pinatas either.
4. The SystemAgain, KISS. If you can't come up with a good reason to model something or show players a statblock for it, don't. If you're doing an RTD, all you really need is a d6. Maybe a simple attribute or skill system if you want to get fancy. For other games, the same sort of simple exp/skill deal is usually good enough. If you want something more comprehensive, crib from an extant system that approximates the style of game you want to run.
5. Graphics/Illustrations: Should I or Shouldn't I?It depends on how fast you are, and how much you enjoy drawing on a computer. If you've got a tablet you use to draw, it's super easy. Otherwise generally I'd recommend staying away from hand-drawn stuff; it isn't strictly necessary, even if players are often attracted by shiny pictures.
I'll leave an example that I've got personal knowledge of.
Here's a game I ran briefly a couple years ago before succumbing to my usual apathy and prioritization of real-world shit. I'll break it down based on what I've just said.
1. This is pretty standard for B12 style suggestion games. I opened with a brief, evocative description of the PC's location and some hints of how they got there, the intent being to grab player interest quickly and reveal information about the setting over time. Note the character sheet, such that it is: all it tells players is that they're not hurt and that they don't have any stuff. That's all you really need for this sort of game. Obviously I had more in my notes, but there's no point overloading people with stuff that's not relevant to them.
On the downside: I had a bit of a map fetish back then. I still do. It's a nice thing for players, but doing it right is a lot more work than it should be, and can serve as a crutch for poor descriptions. I also didn't frame the player choices very well; that's part of why I like the quest system of offering a couple more obvious choices and possibly a write-in option, because leaving things purely open-ended can make people hesitant sometimes.
2. It
is an original setting. Breaking my own rules, heh. 'Course, that's more related to my own problems: I'm pretty good at working out original settings, but I'm inevitably tempted to drop them into games that I abandon after a month or three, never really exploring them much. This wasn't a particularly good one, though, just not-quite-totally-generic fantasy, with the interesting element being the fairly unique magic system I brewed up for it.
3. Yep. There's a solid plot behind what's happening. I knew exactly how and why the PC was in that situation, what the larger-scale geopolitical implications were, and how various player choices might impact the world. Never got that far, natch, because I'm a lazy bad GM that abandons games.
4. I lost the notes for the magic system a couple years back, but from what I remember of designing it, it was intended to be elegantly straightforward. Other than that, all I used was a simple d6 scale akin to what you'd find in a RTD for success/failure of actions. Not the best for modeling progress, of course.
5. As above: map helps with visualization. Images help immerse players in the game. Maps or images that measurably take away from planning/writing or cause the lazy GM to lose interest are not worth it.
Generally...
The Good: Mostly narrative, just enough information and stats for players to know what's going on. A setting and plot that operate independent of what the player does. A simple system for the mechanics. Restriction of knowledge to purely things that the character would actually know.
The Bad: Inconsistent mechanics in the voting. I realized that the open-ended stuff was shit early on and changed it. Limited modeling of action and growth due to the d6 system.
Too much restriction of knowledge; once players got out of the immediate situation they had no idea what to do, because I was too heavyhanded with the metaphorical This Way signs, unwilling to railroad, and didn't set things up so that they could immediately twig onto the larger plot. When I realized that I had messed up, I used a lazy plot device.
If there's one positive lesson to learn, it's that more raw data isn't better, and can't substitute for prose. If there's one negative lesson to learn, it's that you should make sure to have even the little details planned out, and if you don't should take time to work them out consistently rather than improvising if you're not very good at it. Or possibly that if you're going to run games you should make sure that you're not a lazy unmotivated asshole like me.
An addendum on choice: Choice is good. Choice is also bad. If you give players too much freedom of choice, they're going to be confused, lost, or do stupid random shit. If you give them too much freedom in character design, they'll give you overpowered demigods and fetishistic Mary Sues. If you don't ever squash impossible or idiotic decisions, the game might be driven into the ground. If you give players too little freedom of choice, they'll chafe, complain (rightfully) about railroading, and often do their utmost to derail the game out of spite. If you always stop players from doing anything that isn't exactly what you want them to do, you are the cancer that kills cooperative/collaborative gaming.
The key is to provide enough structure that the players don't have any trouble determining what potential routes you're offering, but leave things open-ended enough that a creative player-designed choice is still possible and encouraged in the right circumstances. Some choices might be too restricted by circumstances to allow write-in responses, while others might be so complex that you don't offer any choices and force players to come up with their own solution.