[orbital-decay]

3) Add randomness, mimicking either of the above. (e.g. Roguelikes/lites, deckbuilders, etc.)

Not sure that the randomness in roguelikes is just mimicking the challenge. Nethack is a canonical example of randomness adding to depth. The game is insanely random, but the mechanics are unbelievably deep and diverse, and if you are skilled, you can always avoid death in a myriad of creative ways unavailable for a newbie.

The downside of such a design is its combinatorial complexity, which is also apparent in Nethack, as it also allows plenty of "abusive" behavior. In contrast, DCSS devs aggressively cut features from the game to "streamline" it (aka simplify it enough to make the task of preventing abuses of mechanics easier)

This can be applied to anything skill-based that contain randomness or incomplete information, down to battle royale FPS games - the skill is in to use the knowledge and game sense against whatever the RNG (or a game situation) throws at you to get predictable results.