I'm just curious when and what games are legal to mod and what are the processes I must follow to keep the mod project from becoming illegal. To be specific i'm trying to do a side project while in college. The idea is to make a completely modded version of Pokemon red/blue. The main idea of the project is to see how faithfully we can recreate the game in a modern language (like java, C++, or C#) since the games were originally written in Assembly(I think). It would have the same battle system but updated graphics and potential bugs worked out.
In the context of trying to re-create one of Nintendo's older games, Nintendo won't allow it. For example, a fan-made Super Mario 64 remake received a DMCA copyright infringement complaint from Nintendo, even though it was made as a tech demo for remaking a Nintendo game in Unity. It sounds like your intentions are to do something similar for Pokemon.
More information can be found in this polygon article.
I am not a lawyer, and you should consult one for legal advice, particularly given that you intend to be doing something with Nintendo's intellectual property (they are particularly litigious).
That said, modding a game is generally legal if:
- the TOS of the game in question allows it (or perhaps, in some jurisdictions, does not explicitly forbid it; see the next point)
- you are granted the legal right to modify the software you own a license for by some other law in your jurisdiction, independent of what the TOS says (and/or in a fashion that the TOS is not legally allowed to override)
- your modification does not otherwise break any other, broader laws -- such as copyright infringement.
"Recreating the game in a modern language," doesn't sound like a modification to me. It sounds like it's own project, using (probably illegally) somebody else's intellectual property. This seems like a bad idea.