IANAL but I've paid lawyers to answer this question in the US.
The question is, if you do some work, in your own time, on your own equipment, does your employer own it just because the employment contract says they do?
In California: if the work in any way relates to the employer's business, then yes, they own it. One way to guarantee that it relates to the employer's business is to bring it into the office and use it as part of your job. If your employer is Apple or Google or AWS or Microsoft, then probably anything you write would in some way relate to their business. Write spreadsheets by day, but games by night? All of those companies make games, or are in the games business.
I would love to hear a lawyer say, "Well, it doesn't matter what the employer does, it only matters what your job duties are, so writing games at night is fine if they don't pay you to work on games related things during they day." But I've never been told that by a lawyer, whether I paid them or otherwise.
Everywhere else in the USA: they probably own it. You could write software for washing machines, and write a video game, and if your contract says they own everything you write then they do. You signed it. There's no "but surely not!" defense.
The question is, if you do some work, in your own time, on your own equipment, does your employer own it just because the employment contract says they do?
In California: if the work in any way relates to the employer's business, then yes, they own it. One way to guarantee that it relates to the employer's business is to bring it into the office and use it as part of your job. If your employer is Apple or Google or AWS or Microsoft, then probably anything you write would in some way relate to their business. Write spreadsheets by day, but games by night? All of those companies make games, or are in the games business.
I would love to hear a lawyer say, "Well, it doesn't matter what the employer does, it only matters what your job duties are, so writing games at night is fine if they don't pay you to work on games related things during they day." But I've never been told that by a lawyer, whether I paid them or otherwise.
Everywhere else in the USA: they probably own it. You could write software for washing machines, and write a video game, and if your contract says they own everything you write then they do. You signed it. There's no "but surely not!" defense.