[Fyron]

Can you name such a system and give details on it?

I can't name one, as that would be silly... but here are the basics of an example: if it directly or indirectly harms another person other than yourself, it is immoral. If it doesn't, it is not immoral. Being "moral" does not specifcally matter, as most actions that are obviously not immoral are not necessarily morally good.

Here is another one: if it infringes upon the freedoms (freedom to live, freedom to be happy, freedom to better him/herself, etc.) of another individual, it is immoral. If not, it is not immoral. Again, being "moral" is not a big concern, for the same reason as above.

Neither of these rely on "feel-right" assumptions. They can be arrived from from the fact that harming others tends to destablize society in general, so it is better to not harm others than to harm them. If society becomes destablized too much, you might end up getting killed. This is not an assumption, but an observation of human societies.