If you are to make your own Cave Story game then that will take a few years to learn a programming language fluently enough to make a game that is playable and even then you would not be able to do something so ambitious for your first game, if you look at any game developers history they never made their dream game straight away, they had to make games prior to that so that they could understand design better and get to grips with the overall task of making a game. You need to work in steps and build up to making a game that would be this large, your first project shouldn't take longer than a month or two too finish. Some tips for if you are choosing to make a Cave Story game:
- Look at a few different programming languages and find which one works for you.
- Learn that language well.
- Make a few small simple projects.
- Make a few medium sized projects.
- Make your Cave Story game.
This process will take a few years to do, the best advice is to just be patient and work at a pace that is good for you.
If you are making a mod the same rules apply, start by just altering the default game and work up slowly to making a good mod. Learn the basics of what you can and can't do in modding before coming up with ideas that might not even be possible for you to do.
The main problem you have is that you are being over ambitious, anyone can say that they are going to make a great mod and finish it without understanding the time and dedication it takes to make something truly good, most mods get cancelled for this very reason. You need to know your limits and what it too much, just scroll through the mod showcase section to see how many mods have been cancelled. I am not saying you can't do this, I am just saying that you can't do this at this time. I hope this helps.
