Non-Distributable Closed Betas for Indie Games?

I’m currently designing a game and wish to share it with some online friends via closed beta. The problem is that I don’t want to risk any chances of the beta being copied and distributed.

How can I ensure that my game won’t be distributed? Is there a way that I can upload the game and make it available only through specified Epic Games accounts?

I doubt any game could be 100 % foolproof in stopping distribution during beta/closed beta etc.

One thing you can do though is discourage it. What is the deterrent for people distributing it, apart from ethics/morals? You could make each copy of the game somehow digitally unique, and tell the downloaders this, so that if the copy is found online, you know who leaked it. No idea how you’d implement it, just a thought. I guess you’d need then to pursue legal advice and chase the wrongdoers, but that could be very hard depending on what country they are from, and the laws they live by.

All that sounds a bit too hard, so you’d maybe only want people in the beta you could trust.

Good luck.