Well, I think the basic idea is, making sure you have a solid idea of what your game is centered around, and the general mechanical aspects, maybe the hidden things going on that a player may not even see or directly interact with.. like the leveling system, is it going to integrated in a different way than what is prepackaged in with the software? Are you going to use plug-ins to modify your level up system? Can you invest skill points in something so that you can pick locked doors in the game? Is there combat at all? Mixed in with all that, a definite idea of a story start and a story end helps.. then make up the in between stuff.. Like game starts, you're a ghost trying to get a message to a little girl that could save her life, game ends, little girl becomes a spirtual medium and you're the spirit she talks to the most and you've taken over the wraith lands or something.. What happened in between those two points can fall into place as you make stuff up etc. What are the mechanical aspects of being a ghost like? Surely the normal concept of combat won't be a turn based throw grenades at a mech-armored generic bad guy in a post apocalyptic setting kind of thing, with no sense of customization. You want to think of the "concept" really of how the player interacts and advances on a mechanical level. That really needs to be figured out before you can do much in terms of making a game. It all kind of has to blend together. I just recently played a non-typical rpg maker combat game, where everything was contextual based, but the mechanic of "leveling up" was assigning points in a few stats. I could tell there was some thinking done in that regard. That is the stuff you need to tackle before too much progress can be made.
Now what does that have to do with game length? Everything, because if it's stale and been done a thousand times before, then a lot of people won't get into it. And also, I'm guilty of it, I wanted to create a "long" kind of game, but after playing a few shorter ones, I can appreciate the impact even a short 5-8 hour game can leave if you enjoyed the time you spent with it. So, even though I want to shorten my own game up some, I have to consider the core mechanical aspects. Not everything has to be some kind of 're-inventing' the wheel so to speak, but I changed up money accumulation, and kind of had hidden jabs at current socio-politcal silliness, side jobs, and working on the "leveling" system til I'm happy with it. I definitely had to wrestle with the just because I CAN do something doesn't mean I SHOULD do it things also. You'll get stuck in what may seem like, even may be, a never ending cycle that is probably gonna lead to some head aches that can and should be avoided. Somewhere in this long post though, I should mention, aside from just hoping to make a game, I've enjoyed just tinkering around with it to see what I can figure out, and going back and taking the time to look at other developers games. This has helped greatly for my own education, and saved me from probably going absolutely insane over thinking things. Anyhow, I hope this long semi-rambling message has helped.
