You'd need the ability to side load apps onto whatever devices you're targeting, which is something most consumer devices don't allow out of the box.
Honestly, the simplest method is to place your games in the various marketplaces. I know you don't want to do that, but app stores usually allow you to keep apps private such that you need a direct link to its page to download it.
The obvious downside to this method is that your apps might not pass certification due to content, and there are fees that present themselves for publishing on certain stores(iOS, not sure about others). Not ideal, but unless there are other methods I'm not aware of, this might be the best you're gonna get.