You are not the first person, and certainly won't be the last, to want to make a game. That is why the Game Development forum is here: to help you in your quest to make your dream game.
Your game could be anything, from a fan game based on an existing franchise, to an original creation. There are plenty of genres to choose from, too.
No matter the kind of game you want to make, the core desire is the same: to entertain others. How you go about this, though, can vary dramatically.
This post is your first stepping stone into the world of game creation. It won't be easy, but it doesn't have to be impossible. This post provides a guide to get you started, and shows you what is involved in game-making. If you still have questions (and you will!), feel free to ask the community for help.
Get An [Idea]
You probably already have one of these; you're reading this, after all. But the idea is the single most important part of a game, and it needs to be good. You can't just start off with a whim and expect it to go anywhere; you need to seriously make sure it's worthwhile.
What should an idea look like, then? Well, at the basic level it's a plot, setting and genre. The plot is what actually happens in the game, the setting is what kind of world it takes place in and gives it its "feel", and the genre is the kind of game you want it to be (e.g. RPG, puzzle, FPS, etc.). Of the three, the plot is actually the least important; you can easily rewrite a plot without changing the other two, but you can't just change the genre and expect the plot to still work.
Before you do anything else, you wil need to go over your idea several times and make sure it's a good one. If it's a Pokémon game you're making, you already have the genre (RPG) and setting (Pokéverse), so all you need to worry about is the plot.
If you're not sure whether you've got a good idea, ask the community for feedback! Being able to accept feedback and even criticism is an important skill, but that's for a different article to talk about.
Get Some [Software]
Computer games are played on computers (no, really!), and computers use software. You're going to need some if you want to make a game.
There are many programs available that allow you to create games, and a quick Google search for "game making software" gives you a huge list of them. You'll need to find something that works for you, and allows you to make the kind of game you want to make. You should also find something that suits your skill level. Regardless of what you find and how intuitive it may be, be prepared to do a lot of learning!
Here in the Game Development section, most games are Pokémon games, and most of those are made in RPG Maker XP with the Pokémon Essentials Starter Kit. There are alternatives, of course.
[Learn] Your Software
There's a reason people learn to drive before they're allowed to drive. At least with game-making, you don't need to pass a test first. You still need to learn, though.
Any decent software will have a plethora (lots) of documentation, guides, tutorials, FAQs and the like. Make use of them! This is a hugely important step, and it's not one you'll only be doing once either; you'll be learning new things about your software right up to the day you finish your game. If you know how to use what you're working with, you'll be able to do anything.
For the case of RPG Maker XP, there are plenty of guides and tutorials around the Internet, of much better quality than can be offered here. Don't be afraid to look elsewhere for answers.
You should spend a lot of time playing around with your software, getting to know it. You don't need to (and shouldn't) jump straight into making your game. The goal here is to become comfortable with your software, to learn how to use it at even a basic level.
[Plan Out] Your Game
Haven't you already done this? Wasn't this part of the first step, to get an Idea? Well, no, although it is certainly related.
Your idea gives you somewhere to start from. What you need to come up with now is a full-blown narrative, the story of exactly what happens in your game. This can look a lot like a walkthrough, in fact. You don't need to get every gritty little thing in, but you do need to decide where the player goes and what they do, and where they can't go and why.
You will also need to plan out your world, by sketching maps and town layouts and so forth. You need a decent image of what your game's going to look like. You may want to draw some of your locations in your software, but that's not important yet. What is important is making sure you know what's going on.
There are other things you can plan too, such as characters, weapons, items, how levelling up works, etc. etc. There is plenty to think about.
Don't be afraid to scrap ideas! If something isn't working well, take it out. You can always keep it to one side and look back at it later on to see if you can put it somewhere else instead, or rework it somehow.
You're going to spend a lot of time in this step, since you're creating the whole world and story here, at least in sketch form. Trust me; get things sorted out properly here and you'll be saved a lot of grief later on. Now that you know something about your software, you'll be able to tell whether you can implement a given feature you thought of, which is helpful.
[Learn] Your Software
Wait, this step looks familiar...
Indeed it is. As mentioned before, you're going to be coming back to this step again and again throughout your game's development. It really is important.
The key here is to look at your plan from the last step, and find out how to do the things you said you wanted to do. If you really can't do something, maybe you should take it out. Maybe you'll even learn how to do something else you previously thought was impossible, so you can add it in.
Knowing how to use your software also helps in a more general way. Several people gather a team of developers who all work on the same game, but it can be hard to gather them. Learning how to do everything, at least somewhat, lets you continue to make your game even when you don't have assistance. It also makes your team feel better, as they'll know that they're not being solely lumbered with all the work and that you're actually contributing too. You may not be good in some areas, but if you can at least do something that's a big plus.
[Make] your Game
This is the stage most uninformed people think you start at. Obviously that's not true. By completing the previous stages, you should now have clear ideas about what you want to do, know how to do it, and are able to set yourself decent goals. Because of this, you'll be able to steam through.
This stage is all about making maps, gathering and using artwork such as tilesets, eventing and so forth. It's about coming up with something you can play.
When you are ready to show your game showcase it in the correct area.
Only do this after you've started making your game. Why? Because it shows that you've put a lot of effort into it already, and are just looking for someone to touch things up. If you haven't done anything at all, and ask for people to do everything for you, that doesn't look good, and they will wonder why you're part of the team at all.
As a simple rule, the more you can show that you can do things yourself, the easier it will be to recruit someone else to help you with it. It seems strange, but it's true. We're all donating our skills here, and we'd much rather feel free to contribute as much or as little as we want rather than feel pressured into doing a lot of work. We're more likely to help out if we think we're easing your workload, and less likely to if we think you're just offloading it onto us because you can't be bothered to do it yourself or even learn how to.
You don't need to recruit other people to help you make your game, of course. It's perfectly possible to do the whole thing yourself.
It is important to recruit help according to the recruiting rules.
[Make] your Game, and [Learn] Your Software
This again. You've probably figured out by now that this is what you'll be doing from now on.
As you make your game, you should also be tweaking your plan. You can also add in extra bits, such as side-quests or secret areas. Your plan should be robust enough already that you don't need to make major changes.
Release a [Demo]
This is another optional step. There is no set guide for when to release a demo version of your game to the public, and what it should contain. You should certainly have a firm grasp now on what your game is like, so you'll be able to answer these questions by yourself.
Generally, a demo should have a decent amount of content, and should be of a reasonably high quality. Treat your demo as if it was a game in its own right, and fix as much as you can with it first. There is no excuse for leaving things incomplete. It may not be perfect, but make it as good as you can.
Don't set specific dates for a demo's release; you'll only end up rushing it. You have the luxury of not working to deadlines. Any deadline you do set yourself should be no more specific than "within the next month". The only deadline you should ever be forced to stick to is: "When It's Done."
[Make] your Game, and [Learn] Your Software
Yes, again. Get your game done now. You can release another demo if you feel like it.
[Polish] Your Game
This stage can also take a while. You should have been doing some of this throughout, but now that you've made your game you can really knuckle down and get some serious polishing done.
This involves tweaking graphics and music, fixing bugs, balancing the difficulty, and beta testing. Any feedback you get about your game is really useful here.
You are not allowed to add any last-minute features now. You should have done that earlier. If you've gotten to this stage, your game can do without them.
You've made your game! It was a long road, but it's a big achievement and hopefully everyone will love it. All you need to do now is bask in the adoration for a while, and then move on to your next project...
Game Development Programs
RPG Maker XP (RMXP)
RPG Maker VX (RMVX)
Plugins & Kits
Pokémon Essentials for RMXP
3D Resource Creation
If you would like to contribute to this effort feel free to leave a post with any links you would like to share, be it a tutorial you found helpful or some software or plugins you have found that are not listed. Even just letting us know what we could do to improve this guide is a lot of help!