It is legally now my game.
In most cases, you don't. You bought
the license to play the game,
not owning the game. You could read that in most of the games' terms of service which you usually just click "I agree" and move on without reading it further. IDK if that game has terms of service and EULA. But many games have.
And modify someone's else game is considered hacking. Especially when the game is encrypted and somehow you break that encryption. By answering here means, we support how to hack someone's game which clearly, we don't.
Please contact the developer to add mouse support or you're on your own.
There are reasons why it must be the developer.
- They know inside out of the game better than you.
- They are the developer.
And as I said again, it's not just "drop some script and works" like when you mod many games out there. Do you at least read my point on this?